Drawing Question

[uley]

Very new to the game and trying to figure out a simpler way of make correct calls to flush draws, straights, etc.. if I understand this correctly it goes like this - say I'm on a flush draw after the flop comes down - giving me nine outs or 4.22 to 1 odds for my hand on the flop for the turn - lets say there is $40.00 in the pot - guy ahead of me bets $10.00 giving me pot odds of five to one - I call because the pott odds are higher than my odds to make my hand - or as a rule of thumb if I have to make a call for a flush draw on the flop for the turn the bet that I am calling has to be at least 4.22 times as high as the bet itself - thanks for any input or advice!