1
Check that your desired sticker location is relatively warm and not damp above 13°C
2
Clean the surface that the sticker is going on, rubbing alcohol/Isopropyl or soap and water will work but make sure it is dry and dust/grit free
3
These stickers have a handy transfer tape on them so you don't need to touch the sticker itself. Peel back around a 2 centimetres of the white backing from the top or side with large stickers or just a little on smaller ones, attach this where you plan to put the sticker, pressing down the exposed tape and sticker, you can now slowly peel away more backing and using a credit card or similar to rub down the rest of the sticker, going from one side to the other or from top to bottom slowly helps stop bubbles underneath.
4
Now admire your handy work :)