What is the general rule of thumb post flop for when you are playing a small pair and the flop is all high cards or your playing an ace high broadway and the flop is all low cards?

I've been playing against a lot of calling stations, at the 2nl level am I just to assume they don't have anything near my range and just rail them on every hand in my range even when I flop air or am I suppose to fold any time I miss the flop and hope for the next time?

I know this is a general ass question but it's just such a major issue in my game, I'm good on pre-flop what hand ranges I'm comfortable with in what position and taking advantage of that. It's post flop when I don't obviously have the best hand that I don't know when to cut and run or when to shove it all in.