Wipe down the area with isopropyl alcohol first to remove any left over residue, oils, bike spray etc. Piece(s) of masking tape to gauge where/how high up the lowers you’re going to apply them, so they’re symmetrical each side. Most importantly, make sure you are sure of the orientation of the decals before you apply them.
Warm the old decals with a hairdryer or heat gun ( carefully ) this mean they peal easier and leave less glue on the fork/shock. Then wiper spray/cover with electrical contact cleaner or isopropyl alcohol for a 30 seconds & wiper off repeating to remove any residual glue/contaminants so the new stickers stick well & as above triple check they’re square & right way round 😉