I regularly use Fiverr and Upwork for my side business. Fiver for the quick, simple, items that don't require a ton of skill (ex simple images). Upwork for the professionals.
I may be in the minority, but I don't search for the lowest price on Upwork, I search for the best value. Poor quality costs too much. When filtering applicants I look for strong profiles (pictures, portfolios, and aptitude tests). I also look for people who actually read my posting. Anyone who puts automated replies gets automatically rejected. Lastly, I look for reviews.
If you're starting out on Upwork you will have to build credibility. That may mean taking lower paying gigs to start out. Consider it tuition to build a client list and good reviews. If you do good work, chances are the same people will hire you. And you'll be able to increase your rate once you're known.