How to kill as fox?

I find myself having an easy time racking up damage, but a hard time knocking them out. I know some of his moves kills, but before I can land an fsmash, upsmash, or upair, the enemy usually has enough time to kill me instead at a relative low percentage (80 - 100). I usually continue to rack damage until pretty much anything kills, but this is not optimal at all. Any tips, or known kill confirms you guys would like to share?