When I first started playing poker, everything was about the odds.  I played limit ring a lot and needed to know if certain calls were justified.  My first poker book listed all those "drawing"odds in a neat little chart that I copied and taped to the side of my computer monitor.  It stayed there until I memorized those numbers and hard coded them into my brain. When I started playing a lot more NL ring, those numbers helped me to make good decisions quickly. Below is a copy of that chart with some explanations.

You also need some other numbers ‘hard-wired' about preflop odds for different types of starting hands. 

The odds of flopping a full house or other stronger hand are so low (.09% or less) as to be considered insignificant.

However the following stats are VERY significant.

For instance, if you are heads up, what are the chances that your opponent has at least a pair after the flop?  (31.2% 1 time of 17 he has a pp and the other times he hits one of his hole cards.  A pair on the board doesn't count.)

You will be dealt a pocket pair once every 17 hands and AA once every 221 hands.
You have a pocket pair (pp) and need a set on the flop to continue.  (12.5% or 1 chance in 8)

The flop has a pr like KKQ.  What are the odds of your opponent having another K?  (1.347% or 74 to 1 AGAINST)

If you have unpaired cards, how often will you flop 2 pair?  (Not counting a board pair)
2% or 50 to 1 against!

Your cards are both the same suit, what are the chances of flopping a flush draw?  (10.944% or 8.13 to 1 against)

With paired connectors you have the following chances:

'Made' hands:
flopping full house:  0.09%
flopping flush:  0.8%
flopping straight:  1.3%
flopping trips:  1.3%
flopping two pair: 2.02%

Draws:
flopping open ended draw: 10.4%
flopping flush draw:  10.9%

Hence, 5.5% of the time you will flop a made ‘hand' but 21.3% of the 26.8%  (or 80%)of the time you flop a ‘hand' it will still be a draw with about a 1/3 chance of the draw completing by the river.