The following items can be found at your local Office Supply Store, Art Store, or on-line
The Basics
Drawing pencils (Make sure they are marked 3B or 2B. The "B" indicates the pencil graphite is soft, ideal for sketching. They come in standard pencil form or mechanical pencil form with graphite inserts. Not pictured are another form: retractable pencils with .05mm graphite inserts, great for detail or fine lines.)
Pencil sharpener (hand-held or electric)
Drawing board or drawing table (You can use a kitchen table or desk, just cover it with a layer of plain white paper to protect it.)
Drafting tape (not as sticky as masking tape and is easy to remove and reuse)
Tracing paper (comes in a roll 18" or 24" [46mm or 61mm] and also comes in sheet form usually in a pad)
Plastic Architects' triangle (get one that is 30 degrees by 60 degrees by 90 degrees)
Soft white eraser (get one that comes in a small bar)
Digital Camera (anything from a camera phone to SLR)
Advanced Stuff
T-square or moving straight-edge for your drawing table or board
Watercolor paints (comes in a pan set or individual tubes. See Introduction to Watercolor for specific colors.)
Assorted paint brushes (see Introduction to Watercolor)
Utility knife
Spray glue
Foam core board
Cutting mat
Small block printers roller
Metal straight edge
Architects and engineers' scale in Imperial or Metric (for reading blueprints)