What are you envisioning? I found a very pretty and ornate comb for my hair at JJs House (online) when I bought my dress, and I also found some pretty and simple necklaces and earrings at Kay Jewelers (also ordered online).
I would just browse online and, if you would rather see it in person before you buy it, stick to stores that are in your area so you can see if they show it in stock there.
I would check out the jewelry depts. of all the department stores you can think of. They normally have good selection and will have lower prices than DB, Kay's, etc. for jewelry you may only wear one day.
If you have an idea of the type of jewelry you want, you can just Google it (example, I searched for gold climber earrings) and click on images. The first few rows that come up are usually products (aka ads) so it's easy to figure out where to buy them. Also, if you click on a picture, it brings up similar items, so you end up with choices.
I bought my accessories on amazon.
I haven’t bought my accessories from them, but I have been buying my gifts for everyone from here. It is called paparazzi, the jewelry is $5. Some of the pieces are super cute too and a great price!