Admob mediation Experts

I have a game in which admobs is implemented, the only problem is that we are getting VERY low RPM/ECPM . Usually it gets .04 cents to .09 cents but not more than that. I have read many cases which people say that a normal RPM rate is more than 1 dollar and as high as $10, and that they recommend using mediation to get higher payments or ecpm (payment per 1000 impressions). If you can help me get a higher RPM, by setting up mediation and tunning it, i would appreciate.