Step 1 of 12: The Sellotape method

We're going to use what we're calling the Sellotape method. For this you'll need a standard off-the-shelf screen protector kit (make sure you buy the right one for your specific model of phone or iPad - see our roundup of the best iPhone screen protectors for further advice), plus a roll of clear sticky tape - although we guess that, at a push, masking or PVC/electrical tape will also work.
We're applying a screen protector to an iPhone SE so standard clear tape is the right size here, but if you're applying a protector to an iPad then you might like to use wider clear tape such as that used for wrapping parcels. Read next: How to repair a broken iPhone screen