In free for alls (which generally aren't discussed here), try to zone people away from you and into each other by using moves that aren't laggy. Aim to miss with fairs and Nairs, and retreat the end of each jump so you don't end up near them. If they avoid you, great. You've then moved people into each other. If not, you've either hit them or gotten hit with something that has better range, and act accordingly in each situation.
I noticed a bunch of bad habits, most notably roll spamming, which is really problematic once you have someone with their attention on you (most of all in doubles or 1v1)
I'm not a huge fan of online games, so I'm not gonna comment further. If you have 1v1 vids and/or something not online, we can give you some better advice.