Forum Moderators: skibum
Assuming that you're a genuine novice web publisher and not some employee of ValueClick attempting a thinly-disguised PR campaign, why ask?
Why not just try it and find out?
How are other people's experiences ever going to give you better data than your own experimentation?
As a general rule of thumb, the more risk you take on as a publisher the more money you are likely to sell your advertising space for, given that you are selling qualified traffic.
CPM (ie. pay-per-thousand-impressions) is the least risky for you - all you have to do is put a creative in front of a visitor to your site.
So, assuming that your traffic is qualified, you will make less from CPM than you will from CPC (where you have to get the visitors to click) and, in turn, you will make less from CPC than you will from CPA (where your visitors have to be sufficiently qualified that they will buy from the site they click through to).
But there is no harm at all in mixing and matching - I use a combination of CPM, CPC and CPA.