My first book was also a stitch in time and I loved it. Some years later and I'm probably around 100 books, although I still didn't buy q-squared.
There's this awesome and slightly outdated guide where it's easier for you to pick books. Or just go with your personal favourite series.
Some exceptions that never went on TV that I know are: stargazer(Picard before enterprise), Titan (Riker after enterprise) and New Frontiers( based on a whole new set of characters and by far the funniest of all I read).
https://www.thetrekcollective.com/p/trek-lit-reading-order.html?m=1
Are you against DRM for technical limitations or convenience? I do it for convenience and started writing down before choosing what to buy, but even some short trilogies have mixed DRM and no DRM. I mostly use Kobo for buying but I have no strings attached.