I've been optimzing my ads a lot, but the eCPM is still low - and my CTR is sorta high, but I don't how to get a better eCPM - do you?
Being a cost per 1000 impressions it would seem that either the CTR needs to increase, or the price you are getting per click needs to increase. If people have lowered their bids, then even if your CTR is increasing it is possible for your eCPM to go down because you are making less money for each 1000 impressions. Another thing to think about is that an impression isn't always a unique visitor. So if a single user is viewing many pages on your site without clicking then your impressions will go up without making any more revenue which will also drop your eCPM.
I see, now that explains it - so should I optimize the ads even more, or place different ads up - ie: text, instead of images.