Hi
The best way of applying adhesive is usualy be cleaning the surface first
Then lining it up and applying it
For the pre cut adhesive I find that if you peel the protective film off to about halfway then get a plastic pry tool and use it to press the adhesive into place
Once you are confident that it’s stuck down good I would peel the other protective film off and adhere when you want to it
Here’s a video on it!
[link|https://m.youtube.com/watch?v=AsYamvF8Y1o|https://m.youtube.com/watch?v=AsYamvF8Y1o|new_window=true]
If you skip to the 1min mark that’s when the explanation starts
This video isn’t for your phone but it’s the same process across just about everything
Hopefully this helps
Any questions please ask
Thanks:-)