first of all, some basic tips - this works for me always so here goes:
set up your formation so that it mirrors the opposition formation so make sure your dr is against the ml on their team, and keep doing that for all your defensive positions (have dl, dr, dc, dc, dmc)
use the screenie to help you

here, against a 4-4-2, my 2 dc's are against the 2 strikers, my fullbacks against wingers and my dmc against the more attack-minded midfielder
in the opposition instructions screen, use tight marking and closing down to always for all of these players
but in your tactics screen, use whichever system you like (i personally like zonal marking and tight for defenders)
make sure you have a scout getting a report on your next opposition, this will help you a lot
finally, use alex fernandez as a striker, he is really good if your not a prem team (though man utd wanted to buy him)
romauld boco, owen price and sanchez are really good players too)
try to get jack hobbs and krisztian nemeth on loan from liverpool
sorry for the extra-long post, but i hope I helped