If the pot is 1000 and you have to call 100 to see the flop then it entirely depends on stack sizes, but in most cases you would see a flop.

even with 3 6 , I dont think you are EVER so far behind that you cant accept 10:1 so if that 100 puts you allin then you should never fold.
Certainly if you are against just one other player andyou are holding unpaired cards you should usually be happy with anything better than 2:1 if it puts you allin.

BUT,

In the vast majoity of cases that isnt going to happen.

You should be playing with fairly big stack so just start playing Tight and Aggressive and see where it takes you. Preflop, if the pot is small and your stack is big then when in doubt, fold.

There isnt much you should be calling preflop except small-medium pocket pairs for small raises.