As my friend gladi8tor said, yes, its not rocket science, but this is the newbie section, and that is the reason Im trying to explain things. It all looks like a mountain when you are new. When experience kicks in, you can create arbitrage campaigns while being drunk.
One more hint that came to me just now:
I read somewhere, it takes the same time to promote a 3$ product as it takes to promote a 140$ product. So, go for the big stuff, BUT only after you have some experience. Logging in 12 different affiliate networks and seeing a bunch of zeros can break your devotion really fast. Try something small first, make it sell, marvel on your genius and then push your limits.
And, as halfpc said, look at what other people are doing successfully and try to find out why.