I love instagram, and use it to promote my items.
http://instagram.com/gramzcrackersHere is my personal guide for advertising my shop:
I gained followers by keeping it a personal account, not over advertising (I think that only posting your shop items becomes boring and can easily become overkill). I promote my shop items after posting three or four personal posts (my quilt project, something about my family and maybe an inspirational post). I use hashtags on everything. I hashtag the name of my quilt project, use multiple hashtags. I post things totally unrelated to my vintage jewelry shop. Those are the hashtags that are the main draw to my instagram account.
When I post about the shop, and the items I am selling, I use the Etsy App, on the iphone. I search a particular category, like "sterling" or "rings". I will then screen shot four of the items. Then, I will post those items to Instagram and hashtag them with the following hashtags:
#vintagejewelry, #vintage #vintagefashion #rings (or whatever the item is), #forsale #thejewelseekeronetsy #thejewelseeker #etsy #costumejewellery #jewellery #jewelry
I will also hashtag whatever colors or whatever is also helpful for people to find who are searching. If I am having a sale, I will put #SALE
There are other ways to promote, like giveaways (it will get them to your blogs, and then to your shop) Lot's of people participate in the "giveaways" on Instagram. It will also get you more followers.
Hope that is helpful :) Oh, one more thing - I put a link to my shop in my profile. I think Instagram is a place to be more suttle.