value betting? (they never call!!!!)

[roxtar]

When you have what you're pretty sure is the best hand on the turn or river.... How in tarnation do you get calls? I've been betting out anywhere from the min. to 1/2 the pot and I can't get a call to save my life and it's really beginning to frustrate me. What's a good way to gauge the amount to bet that you will get paid off? Or is there something I'm missing in the whole concept?
I try not to slowplay and give opponants free cards to make their flushes and straights. But all I read around here is that these games (especially low limit ones) are full of fish that will push their own mothers down a flight of stairs if they have any hope of making a straight or flush. That hasn't been my experience thus far in my short online "career".
Could this be a leak in my game that needs fixing or am I worrying about something that's not all that big of a deal? Is there any time that taking down a pot w/o a showdown is bad?