First you need stabilizer( lots of it). Go online and research what types there are. For knit fabrics I use Sulky Sticky (won't gum up the needle) and pin the item to the stabilizer instead of hooping it. You can get hoop burn on stretchy and delicate fabrics. Get Ball Point needles for knit fabric (sharp will pull and snag) look here for a guide: http://www.allstitch.net/content/emb...guide-1023.cfm
You need thread (I bought mine on Ebay). That's pretty much it to start. Practice on used shirts and things to start so you don't ruin a new item. READ YOUR MANUAL!!! I would write this a hundred times. Get to know your machine and all the things it does. I've had mine for almost 2 years and I still refer to it. There's a lot of REALLY good info in there.
If you machine can use it, I would recommend the magna hoop system. Watch the videos. http://www.sewforless.com/category/M...FVhJ2godnmL7KA
Hooping is what makes embroidery a pain in the rear.
HTH! Have fun!!