Installation of the film was made without worries, no bubble present, yet I used to have on my previous protection films, so I decided to take the bull by the horns and take 20minutes watching tutorials on youtube for small tips.
I found the ideal technique that is primarily to clean the work surface with a Sopalin + window cleaner to remove any dust that are causing bubbles.
Then we clean the phone screen with the same technique: + Product Sopalin glass.
Once clean we are preparing to install the protective film (first protection is removed) last time is wiped with the supplied cloth to remove any dust last.
And the technique that works almost every time to avoid bubbles: You turn the phone so as to have the speaker on its side which will help guide the protective film. Is glued only at the speaker portion and front camera and then ON ANY LOOSE, static electricity does the rest of the work and prevents bubbles. There may be 1 or 2 but are relatively easy to remove.
At worst it has 5 other tests. Good luck to you!