Okay, for all you first time stampers, here’s a little about the three basics. Anything else is extra. (Well, stamping without embossing would be sad, but that will get its own post.)
First of all you need paper. You can buy prefolded cards at craft stores and office supply shops, or you can buy cardstock in full sheets and cut and fold to the size you decide you want. And if you’re making a card, you do want cardstock, not typing/printer paper. Pick up a piece and feel it–if it’s a little thicker and doesn’t flop when you hold one piece by a corner, it’s suitable for cards. If it flops you can use it to make envelopes or print out recipes from epicurious. If it’s so stiff you could knock someone out with it, you’re in the wrong store. I said office supply or craft store, not home improvement!
The texture and coating on the paper is also important. There are many, many beautiful textured papers available, but they don’t take an image very well. Although you may want that effect after becoming proficient at stamping, you don’t want to add that to the mix when you’re just learning how to stamp. What you want is a smooth surface, either coated or uncoated. Coated papers come in matte and glossy finishes, much like photography paper, but not all inks will dry on them. Uncoated papers are much easier to find, and work with any ink. Finally, if you’re going to be saving your stamp-art for posterity, use acid and lignin free paper. It lasts longer without breaking down.
Second of all you need stamps. There are many types of stamps you can use. There’s the standard pink rubber stamps you see whenever you poke around the craft store. Those are usually mounted on wooden handles/blocks with an index picture to show you how the stamp will look when it’s used, and sometimes with the manufacturer’s recommended treatment. (ie. how to color it) You can also get these as unmounted pieces of rubber sometimes, depending on the manufacturer and the retailer. Then you need to have a wooden or acrylic block to attach to the stamp. (It can be permanent or temporary.) I’ll post some links on the side bar for you to explore if you just want to order some.
A fairly recent type of stamp is clear acrylic stamps. They usually come in sets, and stick to acrylic blocks all by themselves. They’re great when you need to position a stamp carefully, and don’t want to use a stamp positioner. (Think alphabet stamps.)
You can also get foam stamps in craft stores. These are generally bold images with little detail. They work best with paint rather than ink, and are fun for home decor and kid projects.
You can make your own stamps as well. People have used everything from linoleum tiles they carved themselves, to bubble wrap, which gives a nice texture to backgrounds.
Last of all you need ink. There are three main types of inks: pigment, dye, and permanent. Permanent inks are generally solvent based, and are great for stamping on non-porous surfaces like glass and coated papers. Dye inks are usually water based, so are easier to clean up, and you can create wonderful water color effects with them. Pigment inks are the slowest drying, so are the best for using with embossing powders.
Hope that gives you a few basics, and a little more courage to go explore the paper crafting aisle. As always, I’d be glad to go into way too much detail, if you have any questions.