There are many affiliate networks of all shapes & sizes to choose from.
The most important advice I can give you, is to spread your offers out over several affiliate networks so you never get yourself into a bind financially if a network has to delay a payment, decides to close, or go to non-incentive.
There are 2 types of affiliate crediting systems-
Postback Crediting- What this means is they are setup to automatically credit your offers for you.
CSV - You are required to pull the report & manually credit offers.
While postback crediting may be easier, you need to look around at all offers & rates to make sure you get the highest rates for your users & yourself.