Small PP early: Preflop

[binarysmil]

Hi,

I really wonder what i should do with little pocket pairs (from 22 to 99) preflop early ?

I think most of the time i simply call. It does not cost much and the reward can be big but on the long run, is that +EV ? If not, what should i do ?
Thank you.

Edit: More info:
If its raised behind me, ill call a raise of one BB no matter what. Two BB or more: Depending on the number of callers behind.

What do you think ?