When it's time to buy art supplies, it helps if you go to the store with some ideas about what you want to do and what you might want to buy. Do a bit of research first, and you're less likely to end up making an impulse buy - it's a great pity to have a beautiful boxed set of inks or pastels going to waste in a closet because they seemed like a 'good idea at the time'! I suggest you start with two types of paper - a generous quantity of inexpensive sketch paper for exercises and sketching, and some good quality drawing paper for working on fine shading and finished pieces. A selection of middle grades of pencil (not too hard nor soft), and a kneadable eraser and sharpener are all you need to get started.
Articles on Choosing Art Supplies:
Paper for Graphite Pencil Drawing
Paper for Sketching
Before You Buy Graphite Pencils
Before You Buy Drawing Supplies - pencils, pens, erasers, sharpeners and blenders
Graphite Pencil FAQ - Can you use an eraser? What do those numbers mean?