
There are Dopers who play cribbage on Yahoo?
I was playing crib – well, in the crib!
Find me. I’m cribbage_patch_kid, usually in the advanced lounges. If your rating is high enough, that is. I don’t give ratings points out to charity. 
But as to the OP – like everybody said, practice. And I’m not sold on Yahoo as being the best place to do that. Play a lot with real cards, if you can.
I think Yahoo’s program is a little goofy. The cards don’t seem to fall the same way as they do with real cards. You will have occasions where you’ll get some really odd hands, twice in a game. Or the same hand, more than once. That just doesn’t happen very often with cards you’re holding.
On Yahoo, you can never turn up a 10 or a face when one would help you, and the odds say that should happen at least once in a while. And for some weird reason, they tend to punish you for throwing the right cards away more often than real cards seems to (i.e., the card causing the worst possible damage based upon your throw-away decision turns up frequently, and the cards your opponent throws away blend perfectly with yours and the turned-up card too often).
Anyway, my tips (which may reiterate some of others):
- Avoid throwing 8s, 7s and 5s into your opponent’s crib. Unless I have a double-digit hand, I will break up my own points before throwing the other guy an 8 and a 7. Too potentially damaging. But that’s just me.
I’m not as big an advocate of avoiding throwing 10s into the other guy’s crib as some seem to be here. But try to avoid throwing cards in sequence to one another, creating potential runs.
- If you’re leading in pegging, throw junk cards to start - like a 2, 3, 4, 6, 9. Avoid leading 10s, 5s, 8s, 7s. Avoid making the score 5 or 21.
One trick I frequently use is to lead something I have paired in my hand. If they double it, you triple it for six points. And the laws of averages say they won’t have the fourth. (But it can happen.)
Ditto if you’re in a situation where you bait your opponent into creating a run of three, if you know you can make a run of four before the count makes it a go.
Do this enough, and play people enough, and they will know you do it. So they will start avoiding pairing your stuff up, even when it’s the only one you have! And you can get into their head, and make them play their cards in ways they don’t want to.
A noble game, this cribbage. Stick with it!