My thoughts

Things I like

I love the sense of freedom I have: I'm not beholden to any particular person. If someone rubs me the wrong way, it's extremely easy for me to not work with them anymore.
I love the variety of assignments.
I love how easy it is to switch into new specialties by underbidding others to get a kind of 'unpaid internship'.

Be aware that there are clients who will ask for help debugging code they're writing but (for some reason) don't know how to check the documentation for the libraries they're using, and/or don't know how to ask for help on Stack Overflow.
- One guy I helped with a single line of code I found with a few minutes of searching Google.
- Another guy asked for help with Pandas and I spent a ton of time trying things and writing up a non-Pandas solution, and then after he accepted my answer I asked for help on Stack Overflow and got a 1-liner working answer in about 5 minutes. So I should've just immediately asked on Stack Overflow once the client had given me a minimal example.
- This kind of "be the middle-man for people who don't know better" was basically the entire basis of the business of Westlaw Court Express.
- These clients probably also make good first clients for people just starting on Upwork.
If you're starting out and bidding low to build up positive reviews, don't waste your Connects on job postings that are asking for "Expert" developers.

Start the cover letter with something a little formal like "Hello," to signal that you mean business.
- (As opposed to saying "Hey," or "Hi,")
After two line breaks say something that inspires confidence in the client, like "I can do this." or "I can do this quickly."
- (As opposed to hedging yourself by saying something like, "I should be able to do this" or "I think I can do this").