In my experience, I've had content that compelled companies that wanted to advertise and came to me directly. At the time, I was making pennies on the dollar through AdSense (nil CTR). I showed them facts and figures and wouldn't budge to a CPA offer, rather sign a month-to-month contract or a 3 month contract with a discount or some other 'freebie'. They complied and I had advertisers on and off for 6 months selling space at the price I wanted which killed AdSense RPM earnings. It depends on how well you are at going back and forth to satisfy them and ultimately your own needs. It takes time to negotiate a price, but that price will exceed a CPA, CPM or CPC offer. Being able to know when and how to close helps as well. Good luck!
Companies want to see numbers, in particular traffic patterns and consistency/quality of traffic. Google Analytics reports are needed, for long and recent periods of time, displaying source of traffic and other parameters.