Phone, Laptop and Home Wi-Fi Security Checklist

This home cyber security checklist covers the devices you use every day: your phone, your laptop or computer, the apps on them, and the Wi-Fi at home. Work through it once, a few items at a time. Then repeat the short checks whenever you buy a device, sell one, travel or add something to your home network. You do not need technical skill for any item.

Each section explains why the item matters and gives steps. Longer articles are linked where you want more detail.

Screen locks and stepping away

A screen lock is the first and cheapest protection you have. Without it, anyone who finds your phone can read your messages, open your email and use your accounts.

Choose a lock you will actually use

Use a passcode of six or more digits, or a longer password. Avoid birthdays, repeated numbers (1111) and simple lines (123456).
Add fingerprint or face unlock for speed. They are comfortable and they make a longer passcode easy to live with. Your passcode is still the backup.
Do not use a swipe pattern that leaves a trace on the screen.
Set the screen to lock itself after a short time, such as one minute or less.
Do not tell your passcode to anyone who does not need it. If you must share a device, use a separate user profile.

Lock when you step away

A locked screen only works if you lock it. Make it a reflex.

On a Windows computer, press the Windows key and L together.
On a Mac, press Control, Command and Q together.
On a phone, press the side button once.

At work, lock your screen even if you leave for a minute. In a shared office, a colleague or visitor can read your email in ten seconds. At home, lock the screen when you have guests or children around.

Before a device is lost or stolen

A phone can disappear in a second. Do the preparation now, while you are calm.

Turn on the device-finding feature from your phone's maker. It shows the phone on a map and lets you lock or erase it from another device.
Make sure the screen lock is on and that the lock screen does not show message text.
Write down the details you will need: the phone's make and model, your phone number and the name of your phone company. Keep them somewhere other than the phone.
Turn on automatic backups so that losing the phone does not mean losing your photos and contacts.
Know how to get a replacement phone number (SIM) fast. Find the phone company's official contact page now.
Turn on two-step verification for your main accounts, and keep your backup codes away from the phone. See how to protect your online accounts for that part.

Full steps are in prepare your phone before it is lost.

If a device is lost

Try to find it from another device. If it is near, you may be able to make it ring.
If you cannot find it, lock it from the finding feature and show a message with a way to reach you.
Change the password of your main email account, because it is the key to the rest.
Call your phone company so they can block the SIM.
If it is a work device or has work email on it, tell your employer's IT or security team at once. They can remove access remotely. Do not wait until tomorrow.
Erase the device only after you have accepted that it is gone. Check the steps with your IT team for a work device.

Wiping a device before selling it

A phone or laptop you sell, give away or recycle still holds your photos, messages, saved passwords and signed-in accounts. Deleting a few files is not enough. Use the full reset.

The order matters:

Back up what you want to keep.
Sign out of your phone account and turn off the device-finding feature. If you do not, the next owner may find the phone locked to your account.
Sign out of apps that hold sensitive data, such as banking, email and messaging.
Remove the SIM card and any memory card.
Use the "erase all content and settings" or "factory reset" option.
Check that the device shows its first-time setup screen. That means it is empty.

For a computer, use the official reset option that removes files and not only apps. If you are not sure the data is gone, ask the shop or a trusted support service. Never sell or give away a work device. Return it to your employer, who has their own procedure.

The full walk-through is in how to wipe a phone before selling it.

Updates and unsupported devices

Updates fix security holes that criminals already know about. Many successful attacks use a hole that was fixed months ago on devices that were never updated.

Turn on automatic updates for your phone, computer, browser and apps.
Restart when asked. An update often waits for a restart to finish.
Update the small devices too: your router, your smart TV, your doorbell camera.
Find out whether your device still receives updates. Every maker has a support page that says how long a model is supported. A device that no longer gets updates slowly becomes less safe every month.
When a device is no longer supported, plan its replacement. Until then, do not use it for banking or work, and keep it off your main home network if you can.

Updates matter on work devices too, but follow your employer's rules. Do not postpone company updates for weeks.

App sources and permissions

Apps are doors into your device. Be careful which you open.

Where to get apps

Use the official app store for your phone. Do not install apps from a link in a message, a pop-up or a website that says your phone needs a "fix".
Before installing, check the maker's name, the number of downloads and the reviews. Fake copies of popular apps have fewer downloads and odd names.
On a computer, download programs from the maker's own website, typed by you. Be careful with search adverts: they sometimes lead to fake download pages.
Remove apps you no longer use. Fewer apps means fewer doors.

Permissions

When an app asks for a permission, ask: does it need this to do its job? A torch app does not need your contacts. A map app needs your location while you use it, but probably not all the time. A camera app needs the camera, not your messages.

Choose "only while using the app" for location where you can.
Deny contacts, microphone and photos unless the app clearly needs them.
Review permissions once in a while in your phone's settings, by permission type, to see which apps use the camera, microphone or location.

See which app permissions to deny.

Unknown drives and cables

Never plug in a USB stick or cable that you found or received from someone you do not know. A stick left in a car park or a gift "promotional" drive in the post can hold harmful software that starts when you plug it in. A cable can also carry hardware that records what you type.

Do not plug unknown drives into any computer, and especially not into a work computer.
Use your own charger and cable. In public places such as airports, use a power socket rather than a shared USB charging point, or use a charge-only cable.
If you find a drive at work, give it to your IT or security team. Do not "just check what is on it".
When your phone asks, "Trust this computer?" or "Allow data transfer?" after you plug it into something, choose no unless you started the connection.

Home Wi-Fi, guests and smart devices

Your home network joins every device in the house. Make it a hard target.

Change the router's default settings. Change the router's administrator password from the one printed on the sticker.
Use a strong Wi-Fi password with a long phrase, and the strongest security setting (the router's menu will show WPA2 or WPA3; choose the strongest one that all your devices support).
Update the router. Turn on automatic updates if it has them. If the maker no longer supports your router, replace it.
Turn off features you do not use, such as remote administration.
Set up a guest network. Visitors get internet without access to your computers, printers and files. Give it a different password.
Rename the network so that it does not show your name or address.

Smart devices

Cameras, speakers, TVs, plugs and doorbells are small computers that often receive few updates. Give each a unique password, turn on updates, and keep them away from your main devices. A common approach is to place them on the guest network. We discuss the choice in should smart devices go on guest Wi-Fi.

If you work from home, your work laptop should follow your employer's rules. If they require a certain setup for the home network, follow that first.

Public Wi-Fi and travel

Public Wi-Fi at a cafe, hotel or airport is shared with strangers. Most websites and apps now encrypt their connection, so the risk is lower than it was, but a few sensible habits remain.

Check the network name with the staff. Fake networks with names like "Cafe Free WiFi" are easy to create.
Do not sign in to your most sensitive accounts, such as your bank, if you can use your phone's mobile data instead.
Stay alert for pages that ask you to install something or to enter a code to "connect". Real connection pages do not ask for either.
Keep the device updated and turn off automatic connection to open networks.
Turn off file sharing and, when you can, use your phone's hotspot for work tasks.

When you travel, lock your devices, keep them with you, and do not leave a laptop in a car or a hotel room in view. At borders and in unfamiliar places, follow your employer's travel rules for work devices.

For more, read is public Wi-Fi safe to use.

Common mistakes

No screen lock because "it takes too long". Fingerprint or face unlock removes the delay.
Postponing updates for weeks. The "remind me tomorrow" button is the criminal's friend.
Selling a phone after only deleting photos. Do a full reset.
Leaving the router password on the default.
Giving every app every permission.
Plugging in a found USB stick out of curiosity.
Using the main Wi-Fi for every guest and every smart gadget.
Not telling anyone when a work device is lost. Report at once, even if you may find it later.

Quick reference

Area	Do this	How often
Screen lock	Passcode of six or more digits plus biometric	Once
Lock when away	Shortcut or side button	Every time
Find my device	Turn on	Once
Backups	Automatic	Once, then check yearly
Updates	Automatic, restart when asked	Always on
App permissions	Review by permission type	A few times a year
Router	Change defaults, update	Once, then yearly
Guest network	Visitors and smart gadgets	Once
Before sale	Back up, sign out, factory reset	Every time

Questions people ask

What is the most important setting on a phone?

The screen lock. Without it, everything else fails if someone picks up the phone. Use a passcode of six or more digits and add fingerprint or face unlock for convenience.

Do I need to restart my phone or computer for updates?

Often yes. Many updates finish only after a restart. If you keep postponing it, the old, weaker version keeps running. Restart when it is convenient, but do it the same day.

Is it enough to delete my files before selling a computer?

No. Deleted files can often be recovered. Use the official reset option that erases the data, sign out of your accounts first, and ask a trusted support service if you are unsure. Return work devices to your employer instead of selling them.

Should I worry about my smart TV and cameras?

They deserve a little attention. Change default passwords, install updates, and consider placing them on a guest network so a problem with them cannot reach your computers.

Is it safe to charge my phone at a public USB port?

It carries a small risk. Use your own charger in a power socket if you can. If you must use a USB port, a charge-only cable or a small adapter that blocks data helps. Choose "no" if the phone asks whether to trust the connection.

Learn this in five minutes

The track "Phones and Computers" teaches the habits in this checklist in five short lessons: choose a secure screen lock, lock your screen when you step away, prepare a device before it is lost or stolen, protect information on shared devices, and check, reset and erase devices before reuse or resale. Each lesson takes about five minutes and ends with practice questions.