Yeah the best way to deal with lag is playing accordingly, you’re not going to be able to reflexively do much of the stuff you do offline (well, some of it you will if you’ve got a stable connection and get into the flow of things, but generally I’m no where near as consistent on kaillera) so you’ll have to be more deliberate in your moves, especially in reaction to things.
This goes conversely as well, because your opponent shall also have a harder time doing things on reactio, which sometimes allows you to get away with tactics that would make you eat stuff, so as long as you aren’t predictable there is certainly some things that work that wouldn’t offline as well. I’m not advocating abusing the lag, but knowing that it hinders your opponent as well, and knowing what that may allow you to do.
As far as what you can do about the literal lag that affects the game, sadly there isn’t too much, you’ll experience it regardless of what tools you use to play the games, and more have to play with it, than find a way around it. (Playing on servers close to you with competition that lives close will lower the lag, but in now way will get rid of it entirely.)
Perhaps someday we’ll get an arcade emulator with online play that cuts out the server, and hopefully have ZSNES type latency.