playing weak top pair with position

[tmcdmck]

this is a very common spot and i am never sure what is best. I call a preflop rasier with something like 78s and the board comes down 862 or something similar. the raiser proceeds to continuation bet. do i call allowing him to outdraw me for free but keeping the pot small? do i raise essentially turning my hand into a bluff, and getting myself into a very hard situation if he decides to semibluff shove? what do people think is best, and what adjustments do you make depending on who the pfr is?