I use compost, but peat moss is a good choice too.
Just use good potting soil or compost, if in ground. What specifically do you want to grow?
Thank u Naomi, I want to grow herbs n vegetables.
I don't fertilize the herbs at all. I just use compost and potting soil. If fertilize too often they get leggy and lose their flavor.
Buy some 15-15-15 prilled fertilizer at your local garden center. It is a balance of nitrogen, phosphorus, and potassium. The garden center can tell you how much to use. I grew vegetables commercially and used this all the time.
Herbs do not want fertilizer, they like a very lean soil. They will get leggy and not taste as good if you feed them much.