No one really knows what's best for you but I think that you could start with building your own blog or site and include your favorite ads to it and see how it works for you. Of course you need to make content that attracts visitors to your site first.
Heemmm...maybe you can start to promote your cpa offer with social marketing. send tweet to big twitter folowers is perfect for your marketing
I would suggest you start off with Plenty of Fish or Facebook as these the recommend traffic sources with newbies. Also, for a long term business you can build a facebook page and promote CPA offers to them again and again. Take a look at LukePeerFly's blog, he shows great ways to build a fan page and properly monetize them. Personally, I like using SEOClerks to get some quick fans to build social proof and then go for FaceBook Ads to get quality fans for my page. Good Luck!
Dating offers are best to go with PlentyOfFish. The traffic is insane for dating sites, but do remember to read up on the guidelines.
Depends. Do you have a budget for paid advertising? Are you interested in developing a long term blog or site via SEO, want to build a list, do direct linking, PPC, incent? You may not know yet where your interest lies. If not, the only way you'll likely find out is to try one thing, learn it then move on to a different method. Often times though, people have an idea of what they want to try first, or they figure it out after trying one or two different methods. Guess what I'm trying to say is that there is no one-size-fits-all answer. Some of what others have suggested to me and I've tried, doesn't work for me but they're killing it doing the same thing. Don't forget to take action. You'll figure it out more and better as you go, and as you learn. Best of luck!