I would highly recommend the Joko Engineering series of FreeCAD YouTube videos. I went from being pretty adept at OpenSCAD to getting FreeCAD to "click" by watching this one:

https://www.youtube.com/watch?v=geSQlBczsWY

After that, I spent a month last year doing a daily household item challenge, which really leveled up my skills and now there's no turning back.

https://twitter.com/hashtag/30DayCADChallenge?f=live