Prep is so hard and so important with a deep sidewall. As us ensuring you change your 'angles'
Ensure to pull the skin fold right back to remove all cuticle. Use a thin board (240) grit and use it on it's side like a pencil to really get deep down there to remove all traces of shine.
Then during application make sure you roll the finger over and angle your brush more than normal to make a solid contact with the plate.
Finally during shaping make sure you really get back into the sides to make the product flush and blended. But if the nail is square ( when looking up the c curve) be careful not to file to much into the side of the apex or you will weaken the structure...
Hths