for the cover 3 you can use a streak & fade combo. on whatever side you want to throw to have 2 WR lined up. put the outside WR on a fade route, and put the slot WR on a streak. 9 times out of 10 you're gonna be able to hit the WR on a fade, and hopefully you can make the last guy miss and get a touchdown.
against cover 4, the SF combo will still work but the fade is not a good option any more, so look for the streak. i suggest using compression sets against a cover 4. have 3 receivers lined up on one side and try some routes that go across the field. also, short curls can kill a cover 4 and turn in to a big gain if you can break a tackle.