ok here's how I calculate pot odds (this isnt necessarily the only way)
when the action comes around to you, see how much the bet is that you must call to stay in, and divide this number by the size of the pot (i just keep the fraction in my head, then simplify and round it to a nicer number). Next, you must figure out the odds of hitting your draw. Take the number of cards in the deck that will help your hand (6 "outs" for hitting a j or q as overcards, 9 outs for a flush draw), double the number of outs and add one. This is the % chance of hitting one of your "outs" on the next card. (6 outs * 2 = 12 + 1 = 13%) You can now do one of two things: convert the fraction you calculated earlier to a percent, or convert the percent you just calculated to a fraction. Compare the two numbers. If the first one (the pot odds) is a smaller number
than the chance of hitting the draw, then you go right ahead and call the bet.
I know this is a lot of work and math but its pretty easy after a few times. Hope this really long post helps!