Pay attention to the texture of the board. A 2d7hQs board is going to be a better spot to bet than a 5h7dTd board as far as fold equity goes. A lesser factor but sometimes important one is your own hand. Having 6d8d on that 5h7dTd board should reduce your opponents hand range equity compared to if you had 4s2c, the point is that there are more potential valuable outs to your opponent in the latter example because you don't hold any real valuable cards (4s might have some value to a few combinations, but nothing like 6d or 8d).You might also want to think about opponents that are good to lead against. You might stab flops vs weak opponents for immediate fold equity, or you can bet the flop with a weak hand vs a loose opponent, if you feel pretty good about folding them out on the turn (particularly when you have some equity in the hand, backdoor draws, overcards, semi bluffing, additionally lower card boards can sometimes yield higher fold equity on the average turn card, though this is more opponent dependent, IE folding bottom pair to two or three bets, depends on the opponent and this is where image can come into play).