Anyone who watches fashion award shows knows that jewelry can complete or complicate a beautiful outfit. It is always best just to stay with the traditional rules of pairing jewelry with clothing.
First, if you are wearing an elegant but simple piece you can wear a statement piece of jewelry. An example would be if you are wearing an elegant black dress that is strapless. There are several pieces of jewelry that you could pair with the dress. You could wear a choker to make the dress sexier. You could wear a large necklace that fanned out across your chest. You could also wear a larger stone necklace and highlight the stone. The jewelry will be the statement piece of your outfit.
If you are wearing a casual outfit, do not wear over the top jewelry. Just because you have a diamond choker does not mean that you should wear it to brunch. There is an appropriate time and place and wearing a stunning piece and an everyday event is not the right place. If you feel that your outfit needs something consider wearing a simple beaded piece of jewelry.
If you are wearing a top that have an embellished top then you should consider that top your jewelry. Do not over accessorize. If the top you are wearing is over the top and statement piece then you do not need your jewelry to say something as well. Do not wear a necklace as the jewelry will compete with the top. Wear a subtle pair of earrings and bracelet.