Don here from Shopify. :)
Not a lot of notes from me here as your store is generally laid out well and navigation and products are clear for me.
One thing to notice on your contact page is that there are some language issues here.
I would phrase this as:
Do you have any questions, concerns, or suggestions for us?
Please let us know by contacting us at the following email address: email@example.com
You should also make it clear here that your customers can use the contact form on this page in addition to emailing you themselves. :)
It might also be a good idea to put some time and effort into your product descriptions, as this is a great way to communicate info about your products to prospective buyers.
We've got a good blog article here on how to write product descriptions that sell that you should check out.
How do you advertise your business so far?
We're also available 24/7 via our support site if you need any live support with your store.
All the best!
A bit of grammar errors in the policies and contact us page. Run through a grammar check (OpenOffice Writer, MS Word, or a free online one).
Under Women's of the top nav bar, "Jewelry" is there, but clicking it doesn't do anything. Get rid of it since jewelry categories are already in the drop-down.
Add a bit of color to the site design. Use a similar blue to the logo, or add a jewelry-inspired color like a light gold or sapphire blue or deep medium green. The main idea is to make it appear in context with the merchandise, so not a ton of extra color.
The location of the nav bar at the top is excellent. It's easy to get to...but certain pages could be long-scrolling, so add a "back to the top" button that appears upon reaching middle or near bottom of the page. Here's a tutorial from Shopify for how to add it:
Add Back to Top Button
I don't know what prices are for phone cases, but some of those look a bit high. Try looking up common prices for similar phone cases, and adjust to get sales. More sales at a lower price can generate more profit than a few sales at a higher price. I don't suggest lowering price really far (e.g., a few cents per single order), but research could show a range of prices that the phone cases could be selling at...