Buy solo email is the fastest way but i don't think it is the most profitable as the cost for one solo email is very expensive. Using social media could help but it takes time although it's free. In my opinion, article and video marketing are the best. Try both...
I prefer PPV. 1000 views for $15.00 using LeadImpact. Therefore if 3 people out of 1000 complete my auto insurance zip submit i break even. Design a nice lander, target your demographics correctly and link to your cpa offer. Target urls to match your offer. For example if you were advertising an auto insurance zip offer maybe target people who are buying a new car (usedcars.com, autotrader.com) or people who are searching on ways to save money online, auto forums, etc. Experiment and one day you will find your way to the bank.
You should try and find a very targeted group *(twiter,facebook,pintrest) and drop links, that's if you want quick but not lasting earnings. But if you're serios and have the money what works for me is PPC. I personally use adcenter and change the offer page around a little to make it look more user friendly and easier to fill out. I generally like to use email submit offers because they convert better. But if you have a good plan with targeted audience then you should definitely use some of the higher paying offers.
If you got the money then it's good that you're thinking of doing paid advertising. BUT, I hope you're aware that you're gonna need to spend some money and get in return no profit. That's the testing part. Don't worry, it's a part to success. I'd suggest you 7search for email submits.