This thread asks good questions; here's the main thing. You are already ready for a tournament. No matter how good or bad you are now, going out and getting your feet wet is the single best thing you can do for yourself. It will both get you familiar with the tournament format and will introduce you to a ton of new players who will help you see more of the game than you could ever discover on your own. The single biggest predictor of being a successful tournament player is attending tournaments; just go out there, have fun, and you'll improve more than you might have suspected.
As per the particulars of how to play well, I'd say the most important thing is just being mindful of your play. If something doesn't work, cut it out while you play and later go back and figure out why it didn't work. If you kept going for forward smashes and kept getting blocked and punished, figure out what kinds of situations you were using it in that were easy to block and also re-evaluate why you want to keep using a move that's so unsafe on block that you are easily punished so much. If you on the other hand have something that often works well for you, be able to identify that too and figure out how to maximize it. Maybe you like to throw out a lot of dtilts and hit with a lot of them. Figure out what situations you instictively dtilt and why it hits so much then, and then see if there are other areas in your game that that kind of thinking could be applied to help you. Always seek out strong opponents while doing this too; sometimes certain things will work well against weaker players but will be punished hard by strong players. As you build experience, you'll learn how to read other players and figure out what it really means to read an opponent (which often can be a translation for figuring out what you are able to get away with against a particular someone else).
As long as you do this, play many strong opponents while thinking about your play critically, it will be easy to improve. The technical stuff will come, and it will also be obvious what you need to practice if you follow the procedure. If you miss a tech and lose because of it, your critical thinking will tell you that you're bad at that tech and should practice it in training mode, and it will help you more then than just practicing it now before you've run into it live in the field.
I'd also end by encouraging you to be open minded. A lot of times we pidgeon-hole ourselves as players, and we thus build our own limits. "I'm not fast enough to do that" can easily become "I'm building a weakness of sloth into my game". "I don't use lame spam and camping strategies" can mean "my opponent can play lame against me even when losing and count on me always approaching". Even when it comes to main characters, think about it. Focusing your efforts on one character who will be strong for you can be smart, but make sure you're making an informed decision and always ask yourself if picking someone else might help you more. If you don't, you'll play someone who has similar basic skills to you but is more willing to do more to win, and you'll lose. Always be the one most willing to do the most to win, and you'll never have that problem.
I wish you all the best of luck. Merely asking how to become a stronger player is indicative of being on the right road; just keep asking yourself those questions while actually playing, and it will come.
