1st, it would be helpful if you enable the "Follow" on Twitter button in your Etsy shop.
2nd , search on Twitter for users who have similar interests, products, etc. that you have (they will likely follow your back). Do this gradually.... maybe 10 new follows a day. Keep an eye on recommended follows on Twitter as well as other Etsy folk in General. If you follow me, I will follow you back (I'm at around 1000 followers... quite a few really great ones too).
3rd
Don't just promote on twitter, try to do one promotional tweet to every 3 to 6 non-promotional tweet. This can be updates on your day, helpful articles you're reading, conversations with followers.
4th
If you want your followers to "ReTweet" your stuff... "ReTweet" theirs. Always reciprocate.
5th
#FF is a great way to grow followers. #FF is # Friday Follow I am now more picky about my FFs but I used to FF everyone. I found some great followers this way. Search #FF to see how it works.
6th through ?????
There's so much more! If you follow me, I'll answer any questions you may have and try to assist you building your Twitter Follow Base. :)
Good Luck, hope tou see you on Twitter!