SEO Advice for Marketplace Startup

Hey Indie Hackers,

I'm the founder of a marketplace startup -- we essentially provide tutoring services for developers.

So far, I've been focusing a lot of time on marketing via the following methods:

1. SEO-oriented blog posts. I've written ~20, and now am getting around 50 impressions per day. Is this good, or can it be improved?
2. Individualized outreach on Reddit / LinkedIn, to beginner web developers. I haven't found this very effective as well.
3. I'm a college student, so I've been putting flyers around my campus as well. They haven't done super well either.

I'm thinking about transitioning to some paid advertising, but to any other marketplace founders -- how have you seen the most growth?

Thanks so much!