Too much credit

I think I've figured out a leak in my game: I'm giving my opponents WAY too much credit. WAY too much. I'm putting opponents on sets and two-pairs when disconnected boards come out, only to find out they called down with bottom pair. I'm seeing a low-yet-connected flop come, and am giving credit to the player who bets out, even if I've only seen them take the lead and showdown big-card hands or pocket pairs.

OK, writing this out I think I can add another leak: not trusting my instincts. If I don't think a player is capable of raising with 6-8s, why then would I put them on that when I see a board that would connect with (5s 7s Kc)? More likely than not they'd have something like K 6 off, where my KQ is probably in the lead. I'm putting them on a range, and then when I watch the action after the flop I'm adjusting their range, but I'm always - ALWAYS - making their range a powerful hand that is beating me or can beat me. Often times I'm wrong, and with a flop like that above they'll end up showing down pocket 3's. I need to trust those reads a lot more and stop being such a complete nit.