Also make sure that you are also only counting the odds for the next card, meaning if you have a 1 in 2 of catching one of your outs, keep in mind that you will probably also be facing another raise on the river.
Example:
You have Ac10c
The flop is 6d8cKd
and you are pretty sure that the villain has Kx
You have a 4.2 of catching the flop on the turn, and if you miss the turn you have a 4.1 of catching your flush on the river, so your total odds are about 1 in 2, so if you call his raise you have to be getting 4 to 1 on your money to make it worth while. A few things to keep in mind though are; 1. look for "Hidden Outs" such as the 3 aces in the above example that would give you top pair. 2 Look for places where you have both good fold equity and a good chance of flopping the nuts, these are really good because if the pot is a big enough size you can often times have fairly good odds even if they call you down. 3 keep in mind that sometimes you will flop the nuts, but then have them trumped. Such as a situation where you might have the nut flush draw, but he has a set, so there is a fairly good chance that you will flop the nut flush, but then they will flop a full house trumping your flush.
The easiest way to calculate
pot odds is to just keep a calculator open while you play, then;
put in the number of unseen cards. (52-minus your hand and the flop)
then figure out how many "outs" you have and deduct that, then divide the remaining number by how many outs you have.
Example:
You have 5d7d
the flop is 4d10dQh
So there are 47 unseen cards (52 minus your two hole cards and the three flop cards)
take that number and deduct your outs (13 diamond cards minus the two in your hand and the two on the table which is 9)
you should then have 38, take that and divide it by your number of outs (9)
and you will have your chance of catching your card on the turn (1 in 4.2) divide that by 2 and you have your approximate chance of hitting one of your cards on either the turn or the river (1 in 2)
After you do this for awhile you will memorize most of these figures and you will usually have your numbers without even thinking about it.
I hope this helps and if anyone sees someplace where my figures don't line up please post and tell me where I'm wrong