@RoiBox is right, small sites don't cut it anymore.
I've had a small niche site (12 pages of content only) about 4 years ago and I've tried ranking it for 1.5 years. Well, I didn't sweat trying, don't assume that I've done some crazy stuff. But I did build links to it, optimize and update the content and stuff like that. I didn't create more content simply because I didn't know what else to talk about, there were like few 100s keywords in total in that niche and 60-65% of them were commercial keywords like: guitar classes near me, or ice sculpting workshops in Atlanta, etc...
And the few keywords that were informational I had already clustered in relevant big topics (hence why I only had 12 pages of content), and the highest I ranked was 14 I think... or 16, I don't remember, but it was on page 2 of google. And even that was for a keyword with 25 monthly search volume, so I wouldn't probably have gotten anywhere with that kind of traffic even if I ranked #1...
But anyway, I kept this site for 2 years and after not knowing what else to do to rank it I've decided to sell it (which I did), and I just checked it again and I can see that it has a lot more content now than what it's had under my ownership. The new owner had restructured it a little bit and added a blog and he keeps the site updated with blog posts (although, I can see that many of them are not closely related to the niche of the site, but I'm not surprised since - like I said - there wasn't a ton of keywords in this niche to target, so I can see why he's branched out into different, not very related niches...)
I didn't check the rankings, though as I don't have access to SEO tools, but he must be ranking for something, one can assume....
Anyway, the point is that small niche sites don't cut it anymore, you'll probably have to find a niche in which you can create few 100s posts at minimum in order to rank, even if you target long tail keywords. Google simply doesn't like the average Joe making money, they only reward the big dogs nowadays...