I think we can't decide the eCPM although you can influence the CTR by better blending and suitable ad placement
the only thing that decides eCPM is the ads show up, which is related to the content make content according to that
You can try by posting stuff that is relevant and no rubbish and crap but still there is no guarantee
You have no control over what ads appear and how much is paid pr click on each of those ads. Advertisers pay different amounts for ads.