[jerriep]

I think you are going to run into problems on most of these platforms. Either issues like the on mentioned by OP, or just having to compete against people that are willing to do the job for 1/10th the price that you will do it for.

For me, I got my clients through my personal blog about programming where some people contacted me and asked to hire me. You can also just start being very active on the relevant communities in your niche and build up a reputation.

All of this takes time, but I believe it to be the most reliable long term strategy to get work from high quality clients on your own terms.