When playing leagues I prefer 5* cuz on 6* the AI teams will score more against each other and the elite clubs like Chelsea, AC Milan, and Real Madrid will consistently go a season with only 1 loss and a 3 goal per game average, which is unrealistic. 5* is more realistic cuz crappy teams will often make mistakes like in real life, whereas on 6* they're incredibly sharp and know exactly what they want to do. Doesn't mean u can't beat them as I can go a 38 league match season with only 1 or 2 losses with a good team like Juventus, but its just more fun and realistic on 5* so just stick with it.
Ok I'll share the way I play against the AI and hope u'll improve.
1. Pick a style. Defensive? Attacking? Possession? English style?(long balls)
Defensive: Go to Formation->Team Settings->Auto Defend. This is how Liverpool plays under Benitez. Sit back and try to hit on the counter. Score 1 goal and your team will defend like mad throughout the match.
Attacking: Formation->Team Settings->Auto Attack. This is how I personally play with a good attacking team which also has confident defending. I play as ManU, Juve, and Barca. Puts all the pressure on the opponents half, not giving them a second to relax. If I'm up by 2-0 I might switch back to normal or Auto Defense if my opposition is strong, but this way is tough as you'll just sit back and absorb every attack they throw at you, so you'll be stuck in your own half if they decide to push.
Imo you should never play Normal Attack/Defend on 10min, cuz u won't put enough pressure on their defense, u won't have enough men to support u. So if you win it'll be something like 1-0 or 2-0 most of the times, even against crap teams.
Possession football: good for technically gifted teams with all short players (under 180cm). South American leagues play this way, as do many teams in La Liga. You'll rarely see long balls, trying to walk the ball up from the back. Keep passing it back and forth, all around the pitch and never make a pass that has a chance of being intercepted in midfield or your own half. In their goal area is ok.
English style: good for tall and strong teams, like most English teams. Throw in frequent long balls from the back aiming towards your tall CFs. Get the gauge close to the halfway line and your CF will get it most of the time. If you're on the flank in your own half , and you see your SMF/WF being only marked by 1 defender, wait til their radars become 1, then press :L1:+:triangle: then watch your fast SMF/WF take the ball and send in a nice cross or dribble in for goal.
Crossing: u shouldn't hold a direction if you want someone in the box to receive the cross. Always let go of direction b4 pressing :circle: and you'll send in a perfect cross (with a good crosser) to your CF. Aim towards outside the box and thats where it'll go, to an AMF or CMF for a volley. Aim across the pitch and thats where it'll go, to the other flank.
Dribbling: never ever use :R1: during attack unless you are behind the defence and the space between u and the closest defender is about 2cm on screen. Even then only use :R1: for 2 touches then slow down and smoke the keeper. Players with good dribbling+dribbling speed will push away from the defense automatically in close quarters. It doesn't seem like they will but trust me, use Ronaldinho or Eto'o, run up to defender without :R1: or :R2:, then when your close go down right or up right (if your playing left to right) and they'll suddenly have a big boost of speed and kick the ball further.
Only use :R1: for defense if you lost your man and he's racing towards goal, but this shouldn't happen if your defense is well organized.
Last but not least, don't take off star players if your losing or tied. You may think that they're crap cuz their stamina bar is in the red zone, but your subsitute won't have nearly as many stars or none at all, and even if he's 100% fresh, he might not be as consistent, he'll blow chances, and he defenitely will not run rings around a tired defense, unless the player ur subbing on is better than the player coming off. Check my other thread about fatigue for more info on this subject.
Hope that helps, enjoy the game. If u need any help in other areas just feel free to ask me.