Let me start of by stating that I am still fairly new to this, and no doubt still I have much to learn. Okay now that that's out of the way. A few things I've learned is do some reasearch. Try different pools to see for yourself, the fees seem to vary from pool to pool. Don't believe everything you read; just because you see more glowing reviews than nasty comments..
Each pool and each user's needs differ; an advanced member may be making their mortgage payment from just a few days worth of mining; but these people have been doing this a while and THs upon THs. You on the other hand just broke the bank and maybe starting with a few GH..
Anyway since February.. I've tried several pools and this what I've learnt. (keep in mind I'm still a beginner with just a measly 49 GHs).
BTCGuild 38 hours 35 shifts, 49,328 difficulty 32/64 shares.. earning .00148993
eclipse.. start time 2:22 am.. starting balance: .00000256 around 11,000 shares varied difficulty..
ending balance just before switching to cex-io 0.00102356.. just shy of 14 hours
let's throw cex.io in the mix.. i have earned the least from them but - will give it another shot
and just for good measure.. slush's pool might be great if you have the GHs
f here are difficulty changes during your mining that will effect your results. Also I might suggest looking at pool types. For example BTCGuild "luck" plays a factor you could hit it on good or bad day on solving.