You need to test to check which have best rates. Because my traffic is different from you, so i can have bigger or smaller cpm than you. From my test, exoclick pay less, then popcash (here is the trick - they have bigger cpm rates but count only 1ip/24 hours so after a day you will get less earning than other network with small cpm but count every impression) and the winner for me is popadsWhich ones have the best rates?? my traffic come almost 90% from portugal
I would advice you not to use pop ups!thanks for clarifying... any more tips