Here's an important tip regarding jewelry: Don't think of it separately. Jewelry should simply be one component of your overall look, which includes your clothes, hairstyle and makeup. People who get caught up in things like jewelry end up looking gaudy or odd.
The easiest way to learn how to do jewelry or clothes dressing is to scrutinize people who do it well. I study pictures online of "street style" as well as celebrity street/airport looks for ideas on how to integrate my looks. This is very easy to do and recommend it. With a little shopping around you can find economical clones of most anything you see.
That said, the best use of jewelry is usually very subtle. Most women who do style well only wear one or two less noticeable jewelry items that support an outfit. Usually it's just the earrings. The main areas are earrings, necklace, bracelet and, sometimes, pins or hair ornaments. Wearing more than two of these at once is probably too much. Keep it simple.
Your eyes are your best source of tutorial for this, though. Look around at what other people wear.
