Draw poker hand from the SB

[SoCalPat]

I'm in the SB in a five-handed 1/2 game at Paradise. All limp to me, and I've got a pair of 8s with four to a flush.

This is an obvious complete here, but do I try to improve on my pair or do I go for the flush? What about raising? What if I held a slightly better pair, such as jacks or queens? Is there a dividing line when determining which direction I go with my hand?

FWIW, I went with the pair and won unimproved.