If you need to make money right away, I strongly suggest you reconsider upwork (don't know the other sites you mentioned). I know a friend who worked on it as a dev. I use it as a client. The money from initial contracts might be bad, but it has the potential to turn into a more lucrative deal with a particular client (if you prove your value). This is a great way to build up experience as a consultant .. you can then say you worked as a consultant for X, Y, Z big name brand. Here is the thing .. pick your customer carefully. You want to make sure you are working with a customer who is as tech savvy as you. I work in deep tech so was able to communicate very effectively with my upworker, we were able to estimate things similarly, etc. I have seen postings on other free lance sites where someone wants you to build a highly scalable version of twitter for 50 bucks. You want to be able to avoid those people.