well there are a few general rules you can learn.
after the flop, the odds of you hitting your hand by the river is ~ outs * 4.
after the turn, the odds of you hitting your hand by the river is ~ outs * 2 + 2, unless the number of outs is less than 5, in which case it is outs * 2 + 1.
So if you have a flush draw after the flop, you have ~ 4 * 9 = 36% ( it is actually 35%) of hitting your hand. If you have a flush on the turn, you have a 2 * 9 + 2 = 20% chance of hitting your hand. So you would be getting
pot odds to call after the turn if somebody gave you 4:1 or better odds to call.
As for general %s, an underpair vs overcards is between ~50-56% in favour of the under pair...the lower the underpair the less its odds (board can 2 pair higher occasionally) and suited connected overcards have better odds. JTs vs 22-77 actually favours JTs, but in most cases the underpair is ahead.
overpair vs underpair is about 80% for the overpair.
overpair vs undercards is about 78% (vs suited connectors) to about 87% (non suited unconnected undercards).
dominated hand...ak vs kq, aj vs jt etc. it is typically ~70% for the hand with the higher kicker.
Then you have the situations like a7 vs jt where you have one over and one under, or At vs K9 where you have one over and one mid and those can range quite a bit. Typically, a situation like a7 vs jt, where neither are suited is about 55% for a7. If it was j8 instead of JT, it would be closer to 57/58%, because of the reduced straight possibilities. If one is suited, you had a few % points on to that side. AT vs K9 is closer to 65% i think if neither are suited. If it was J9 it would be more like 62% because again some straight possibilities open up.
None of these last examples are that useful/essential however.
