How to set up a new Admob?

Question

Windows phone

Good afternoon.
60 days ago I published my first mobile application, 30 days ago I connected Admob to it.
At first I was getting $5 a day, by the end of those 30 days I was getting $1.5 a day, that's 1 cent per click.
The decline in income was gradual.

date        fill    clicks CTR    eCPM   revenue 
03.12.2015  99,52%  162    1,29%  0,37$  5,23$
31.01.2016  99,67%  158    1,32%  0,12$  1,57$

I did not set up admob.
Tell me what I need to do so that my income does not decrease, what simple steps do I need to take to set up a new Admob?
Thank you.