Can't exactly make you good at tournaments' but other then helping you be good at your character i can tell you this
Mind Games are a big thing try to use them against your opponent so they can't catch on to you(don't make your moves a pattern and casual, change it up)
Another thing is never roll towards anyone(should be a given)But catch them when they do a bad roll and PUNISH!
Also Don't forget to edge guard to the best degree you can, Ike seems impossible to edge guard so i wouldn't attempt on him and also matters what character you will be using also.
Try not to use moves with a lot of lag/down time unless your chance to hit is really good(Of course know one is perfect we all will miss but play it safe and choose smart times to use these powerful moves such as when they roll towards you or are coming back to the stage)
See if you can study your opponent look for a pattern. If you find that pattern! Great, that's when you can use your KO attacks. Otherwise if they have good mind games try to study there mind games but a pattern will be hard near impossible to see if there good at it.
Last, if they are shielding a lot when your near them make them pay by grabbing them a lot.....some people seem to shield a lot at horrible times so punish them when they do so!
GL!