The best hands to start the game with are
A-A, K-K, Q-Q, J-J, A-K, A-Q, A-J, 10-10.
The power of your pair is affected by its size, how many players are in the pot, what comes on the flop, the turn and the river.
For example, if you have J-J and the flop comes A-K-Q the value of your two jacks would be wasted because someone else might have one of these over cards; an A, K or Q. On the other hand, if the flop came 10-9-8 you would have hit a good flop, having an open ended straight draw and an overpair.
If you have a pair and flop a matching card, you have flopped a big hand … trips or three of a kind.