Problems Scoring:
-If you are not getting many chances, buy a player with high creativity or several forwards with high heading, and a decent corner taker.
-If you are getting chances but not converting them, buy players with high shooting and heading ability.
Leaking Goals:
-Every shot goes in - this tends to indicate a bad goalkeeper.
-Permanantly under pressure - this tends to indicate that you have a weak midfield as opposed to a poor defence and that they aren't holding the ball up and giving the defence some relief. Try either packing the midfield with more players or switching to long ball tactic, if you are not already using it.
-Poor defence - if you have few good defensive players, then try playing 532 with midfielders in the wingback positions and your best defender in a sweeper position in the centre, usually he will mop up any strikers who get past your weaker defenders.