In one study it was found that frequent testing of material is better than simply studying. With testing of material you are actually practicing memory recall. Studying is only one piece to a puzzle. Testing actually as all those pieces of the puzzle at one time.
This same idea can be applied to Brawl I think. Even if you are practicing C4 teching and stuff you are only have one piece of the puzzle. Actual matches contain all the pieces. Now, yume is missing out on someone to play. Well, you can recreate matches using the CPU. I do not care what anyone says, the CPU is a great learning tool if used in moderation.
All you have to do is pick up some area of brawl you want to practice, see if you can duplicate it somehow and then start practicing it. Once you think you have a feel for it move onto a few CPU matches and start applying it as you play. Eventually, you will start getting that new skill ingrained and it will come out properly when the time comes.
For example, I want to learn how to DI MK's Tornado. That is something I can somewhat recreate in training mode. However, it's when it's unexpected you need that reaction to SDI the first hit to pop out. That is where playing the CPU can come in handy. Play MK and then try to SDI the moment you get caught in MK's tornado.