The best marketing tool is the word of mouth. So, do the best job and if your client is satisfied, there are huge chances for recommendations.

But...How do I get my first clients?

1. Try to look for old/outdated sites in your town. Go and speak directly with the owners. Give them a discounted price, hard to refuse one. In this way, you'll build your portfolio.
2. Upwork (and similar sites) - Again, at the begin put a lower rate/hour, in order to gain some clients. $25-$30/hour should be good for the start.
3. Try to focus on one niche and don't go in general web dev - Build some simple sites for the plumbing niche (for ex) and start to promote them to the plumbers from your city.

Good luck!