So really what you want is an ad system. Have you thought about trying to get in with someone like $1? They run ads on a lot of blogs, and unlike Google or any of the major players, the ads always seem high quality and targeted to the readers. As for paid social media promotion, I'd advise against it. It turns people off, can be against the TOS in some places (like Reddit), and seems to be more trouble than it's worth. Another good thing to do might be to try and get some of your articles/posts sponsored, and then just put something like "This post is brought to you buy so-and-so" at the top, followed by a paragraph of ad copy. Ads like that aren't blocked by ad blockers, and don't seem to bother people the way social media "promoted posts" or ad banners do. And to do that, you don't need a website form; instead, you need to do direct outreach. However, the fact that you're not on self-hosted wordpress means you're going to have massive analytics problems. There are wordpress plugins that will let you dig into your posts, and get data about number of impressions, unique viewers, post reach, etc. Advertisers are going to want all of that stuff. And as far as I know, wordpress.com won't give you any of it. Instead, they keep all that info to sell to advertisers themselves. Plus, they tend to take a dim view of blogs selling there own ads, because wordpress wants to sell that ad space themselves. If you wanna make money, you really do need to control the hosting yourself. You can go somewhere like Dreamhost and get a decent starter hosting package for less than $10. A single advertiser would pay for a year's hosting! And self-hosted wordpress is really easy to set up. Plus, having your own domain looks much more professional.

Thanks!

Best of luck on your search.