Suited connectors & small pairs require one of two things:
1) Initiative & fold equity - the ability to win the pot by getting your opponent to fold (usually by light 3-betting or continuation betting).
2) Implied odds
- Knowledge that your opponent holds a very strong hand preflop, but that is unlikely to improve beyond one pair postflop. In addition to this knowledge, you need to have enough money left in your effective stacks to get sufficiently paid off when you hit a big hand.
If you don't have one of those two things, just muck'em, because they're just weak hands. And be sure not to change which (#1 or #2) you decide you have mid-hand, because its pretty rare that you have both.