When attacking, pass ball around until you get a timed finesse angle. Spam timed finesse until goal. If one Vs one, drag back and work that sweet timed finesse angle. Don't worry about power shots, they are not required.
When defending, just keep dropping deep until one of your defenders intercepts the ball. If opponent is a good player (finesse worker) try to block as they get angle. If you can't get there with defender in time, move goalkeeper. Do not tackle, it doesn't do anything.
This is not a football game.
Edit: Extra money saving tip: You can do all of this optimally with ANY players, so save your money and don't buy a better team. It will not help out progress further.