It depends on what type of network etc your looking for, I use adult pay per sale networks (in my sig)
since clickbank i feel like is the easiest to use, I would start there and find a high gravity product.
I would say Ads4Dough is good for beginners as it's really user friendly, as well as RevenueGateway since you get good support there
I've had a lot of success with PIPS and other programs. Currently involved with those in my sig. Nice thing is that the support and mentoring is there. A lot of benefits to teach you step by step.
I would suggest checking out Market Leverage. They are an awesome network with a wide range of offers and staff always willing to help. You should check them out in the link in my signature. I also wrote a review about it here. http://www.jeremiahcooper.com/?p=20 If you need any help throughout the signup process and after let me know. You can catch me on AIM at Sanguinan56.
I make a decent monthly off of people search commisions. The trick is finding one thats legit, took me a year and a half to find it after i locked down the right phrases, kept getting skanky ripoffs affiliate programs, finally found one and the money is great. Not millionaire great but glad to see the check every month great. Very low refunds. I don't regret the time put into it. Check out my sig i just changed it now.