yeah, there's nothing you can do to make a paintjob that will last. Sand, prime, paint, then clear coat over it many times for best results. Car paint clear coat works best (made for a huge temperature range and flex range). You can get some of that stuff on your skis by taking them and a 6-pack to an auto shop where they paint cars and asking them to use the extra clear coat in the bottom of the sprayer on your skis after each car for a couple days. Best of luck!
best paint to use is oil based enamal paint. rustolium is a good brand. but yea sand first. helps the paint stay a lil longer. whenever you paint them youl see chips after a week and ul probably have to redo em after a month. just cuz paint vs edges isnt pretty after a while