I started making jewlery this past summer (for myself mostly, but also for gifts, and with the possibility of selling some in the future, when I feel like I'm a "pro" at it!).
I did a lot of reading first (which is my usual way of learning anything new), then took a couple of classes at a local craft store to get me started. (I just couldn't break through into actually doing the jewelry making until I took the class, even though I'd bought a lot of beads and materials, and had designs for several necklaces I thought of making).
There are several types of jewelry making, depending on what interests you, including.
1) bead stringing (I started with this)
2) wire work (making your own components by bending and shaping wire, or making bead links using eyepins and connecting them together or to lengths of chain, or both, or making dangles using headpins. This is something I've gotten into as well, and that I prefer, especially combining bead links and ready-made chain, OR making my own chain using jump rings and chain maille techniques)
3) soldering (not something I'm into, as I don't play well with fire!)
4) bead weaving (using little seed beads to make almost 'fabric'--not something that interests me at all, I hate working with anything smaller than about a size 6 seed beed: they're just too hard for me to see well).
There are other types of jewelry making and techniques as well, such as making your own beads with polymer clay or metal clay.
You might want to start with a book like "Teach Yourself Visually: Jewelry Making and Beading" which presents a variety of techniques, so you can discover which ones you are attracted to, as I did.
A good book for stringing is "The Absolute Beginners Guide to Striging Beaded Jewelry" (there's also a DVD you can get by the same name; I don't have it, but IMO, it's a great idea to be able to see technique).
An excellent DVD for wire work is "Creating Wire Beaded Jewelry" by Linda Jones.
You can also find some jewelry techniques videos on Youtube (some for making a particular piece of jewelry, but also many of specific techniques, like making a bead link, or making your own clasps, etc.).
The equipment you'll need depends on what type of jewelry you are going to make, so decide that first. Then, buy the best equipment you can (tools with a box joint are the best---if you look at them sideways, the hinge should look like a rectangle on the bottom being embraced in an upside-down "u" shape, and not like two interlocking "L' shapes).
Catr mentioned Etsy, which is not only a good place to buy jewelry, but sometimes a good source of equipment (some of the jewelry makers sell kits for jewelry making or tool kits, etc.).
One of the online places I buy materials from,
www.eebeads.com , has an idea gallery with instructions for making different types of jewelry (you have to know the basics already, though) along with a materials list you can just click on. I've done several of their projects (as well as some other 'kits' I got from other sites) as a way of learning and practicing various techniques (some of your first projects may be more at the level of "prototypes" or "practice," expecially if you take a class that provides a kit, which is usually of cheaper materials, like an 'all-in-one' tool that supposedly does the job of 3 other tools, but doesn't do any of them particularly well, LOL!)
As for selling jewelry, it's possible. The woman whom I took the classes from started making jewelry about a year previously, and was making some money selling some of her things (very "crafts" style, for the most part, which appeals to a certain consumer). She also makes some money doing jewelry repair and reconstruction (like restringing a strand of beads).
