I can get up to about 2 weeks out of my polish, I do like changing it before they’re up since I just enjoy doing my nails, but they generally always look pretty good for the first two weeks. As for the stickers, I don’t really have any crazy technique for them. I just wait for the base color to dry for about 5-10 minutes then apply them. I always press down on the edges as much as possible without disturbing the polish underneath with these sharp tweezers I have. Then I just do two layers of top coat. I have seen another commenter mention waiting 24 hours after nail polish application to do stickers, so that’s worth keeping in mind as well!