I have, but with zero success. I've read awful things about Toptal and PeoplePerHour, so I didn't really go for them. Upwork seems to be filled with developers from various parts of Asia where the low cost of living allows them to bid way lower than what I would charge. The quality of work also seems pretty bad, from what I can tell (one-sentence descriptions, bad grammar, crazy low budgets, etc.).

I've seen advice like, "If you charge high instead of trying to compete with low bidders, you'll be taken seriously," but then there's the issue of having 0 clients/reviews/ratings, which make it hard to command a high rate.

I did have one client on Codementor.io! He didn't give me a review, though, even though we had three sessions and he seemed to be super happy with my help :/