I've had 3 brother embroidery machines, loved them all, I have a Innovis 4000D now, think that's my last one for a while, I embroider on EVERYTHING.
Read your manaual! It's your new best friend.
ALWAYS turn your machine off before cleaning the bobbin area of dust and thread debris. I didn't once and knocked my sensors out of whack.
I don't buy/use a ton of stabilizers. I use a lot of the sticky stabilizer, You hoop the stabilizer, then just press the project down on the stabilizer and it holds really good. I also put water soluble stabilizer on top of every project I do because it keeps the threads from sinking down in the fabric. Both are pricey but if you use your 40% off Joanns coupon it's manageable. And when notions are on sale, it's 50% off.
I have cutaway stabilizer but I rarely use it so if you get any it will probably last forever. I have used lined paper, computer paper, and used dryer sheets for stabilizer. If you need stronger stabilizer, just add more sheets.
I buy my supplies at Threadart. They have sheets of stabilizer really cheap, 200 for less than $20, they are iron on but I never iron them on, just stick them in the hoop. They also sell polyester high sheen thread in sets reasonably priced. They aren't name brand like Isacord, but I bought the sets for the class I teach and my kids have never had any problems with it and the results have been beautiful.
The only thing I stocked up on when I got my machine was bobbins. I mostly only use black or white thread, mostly white. After I am done with a project I thread more bobbins. I usually have 6 white and 3 black when I start a new project. The other thing I bought was extra hoops, they are so dang expensive, but I bought an extra one in the 2 sizes I use the most so I can have one in the machine and one mounted and ready to go when the one in the machine is done. I do a lot of multiple projects.