

Also worth reading the books he co-wrote with Stephen Baxter.
The first book is ok, but the rest of the series is pretty meh. Still bought and read them all as a Pratchett fan, but I wouldn’t recommend them to others. If you want to expand past the Discworld series, Good Omens is a much better recommendation. Also Nation is a really good book too.
Upwork publishes which skills are most in demand on the platform every year: https://www.upwork.com/resources/in-demand-jobs-and-skills
That should be a good starting point. See which of those you’re interested in and can be learned online.