I actually do think Upwork is a good way to start but you could 1) Build a network - go to product meetups (assuming you're a dev) 2) Contact agencies near you

I actually do think Upwork is a good way to start but you could 1) Build a network - go to product meetups (assuming you're a dev) 2) Contact agencies near you and see if they have contract projects you can hop on 3) Use other sites - Toptal, Freelancer, Remote, Gigster, etc.