I Stink! I need Advice.

The topic pretty much says it all. I started playing online multiplayer this evening and lost about eight matches in a row after winning my first match. Apparently I am no good. I play in 2D mode where the AI moves your characters and I make minor adjustments where I think it necessary. I do the actual button inputs for the shots and do not just hit X for simple shot so that I get the best shot that I can. My opponents seem to hit everything back at me that I hit to them but they constantly get the better of me when they hit it back. One strategy that I have found that works really well is to hit a fire flower shot in one direction which knocks my opponent off balance and then hit a star shot in the other direction but of course without being able to determine when each shot type bonus appears that only works out for me on the luck of the draw. Any tips?