The way I do it:
Get some alcohol wipes (or the ones you get free with KFC meals lol) and wipe the top of your windscreen where the sunstrip is going.
get some masking tape over each end and get some1 to place it over your windscreen while you check the height of it and how central it is
Once happy, tape it down
Carefully peel the backing off it and stick it down as you go along.
Once its all down, push firmly over the whole thing again to make sure you get rid of the little air bubbles
then remove the front paper if there is any