The Superior Threads website is a great place for general education. Sure, some things are a little biased because they sell the products but the general info on needles and thread weights and things like that are spot on!
https://www.superiorthreads.com/
Education tab to the far right of the bar
I also like checking in on Bob's Jokes...
(think those are on the bottom, or maybe you have to be logged in)
I am not affiliated with the site, other than I started using and loving prewound bobbins from them and I usually just buy my thread directly from them. No complaints.
edit/PS: I typically use universal needles, but I also like the Microtex Sharps for working on batiks or finely woven fabrics. I prefer to piece with a 10, will use a 12, and quilt using the 12 or 14, so I usually buy the three size multipacks when they go on sale.