Don't waste your time with 7Search, their traffic is absolute garbage. Anyone that tells you they're able to improve the quality of traffic to the point where it becomes profitable by blacklisting bad sources is lying. Search around a bit and you'll find a whole host of malware related to 7Search click spam, just stay away. As for the rest of your question, you really just need to pick quality offers and choose a suitable platform based on that.
Adwords
Bingads
Those are good for PPC.
Facebook
Twitter
These are fine social marketing platforms.
Start out spending small and learn to optimize your campaigns, it's not something you'll pick up and achieve success with overnight.