Seems you already have the ball rolling. I started off similar to you, working predominantly with YC and other incubator startups. Tapping into those existing

Seems you already have the ball rolling. I started off similar to you, working predominantly with YC and other incubator startups. Tapping into those existing networks is what kept feeding me with new work. So leverage what you already have and ask your past clients and their friends for work or even just letting them know you're available to give advice/critiques on what they're doing (that will hopefully lead to contracts after you’ve shown your ability to solve problems).