Thread- I'd start with some basic colors of polyester. I've used Isacord for about 16 years and never had a problem. Their palette of colors is the largest I've seen. After sometime you might want to invest in some nylon , the sheen is nice but not as practical. Stabilizers- Floriani has a good assortment. Depends on what type of embroidery you want to do. I like to use an iron on mesh for knits , etc. use a sticky a lot for items I don't hoop.
Tools- pair of long nose tweezers, scissors with curved tips for nipping thread ends, lots of bobbins-- I like bottom line pre-wounds in neutral colors: black,navy,beige,white,grey,red.. Keep a notebook of your projects with the designs used, where you have them filed, thread changes you made, any problems you may have encountered.
That's a start. I've been doing machine embroidery for almost 20 years, have thousands of designs and have learned much by just doing it. If you would like some titles of books that are good resources let me know, think I have everyone that's been published.
Diane