For freelancing sites, you need to focus on stuff established
businesses need and shy away from anything catering to individuals or startups.
Payment is all relative. Someone with an idea for a new social network might think of $10,000 as a lot of money, even if they want an entire app with lots of features built from scratch, which could be a months' long job. They will vastly underestimate how expensive this will be, particularly if they don't have technical backgrounds.
Meanwhile, an established business might pay $1000 for something that takes a few hours and think nothing of it, because they are thinking in terms of value to the company, not "I don't want to blow through my personal savings".
I hired freelancers at my last job. When going through candidates, I didn't look for the lowest bidder. I looked for someone who charged a reasonable amount who looked like they knew what they were doing. For example, one guy we hired charged us $400 for something that probably took him two or three hours. Considering that he was working out of Russia, this is probably a pretty good wage. Some of the bids were for $50-100, but from my company's perspective, $400 was nothing anyway, so I looked for someone with great reviews and who seemed like they knew what they were doing. I think we found the guy on Upwork, but we ended up hiring him directly to do a bunch more work after that.
I think that if you are targeting well-paying work, look for things that appeal to businesses. Businesses use Excel, so work on your skills in integrating Excel with your favorite programming language. Lots of businesses want web scraping, so learn that. Businesses might have old code written in language X. If you find the right opportunity there, it could be a long term partnership that can be fairly lucrative.