It's astonishingly easy to spend a lot of money while being a self-published author. Far more than you could ever hope to make back in the first few years of writing (unless you somehow get lucky). I've discussed briefly before things that I feel are definitely not worth the money. So I thought it would be worthwhile to mention things that I think are worth the money. Or, at the very least, produce solid results.
1) Cover art. Yes, this can be tricky and expensive as a short story author since you're cracking out a new story every month. But make an effort to put nice covers on what you feel are your "feature" pieces. Stories that seem to sell well for you or stories that you want to become known for. Good cover art can only help this cause.
2) Facebook ads for your FB fan page. Not for anything else. Just for your fan page. Facebook users are "like" crazy. Having an ad run for a few days on FB is a great way to go from 10 fans to 150 fans. Not all of these people will become loyal followers of every work, but that's a solid base of people that you can go back to and make announcements. You never know what might interest someone.
3) Google ads for your blog. You don't even really have to spend actual money on this. Google frequently has ad coupons for $75-100. Use 'em! It's a great way to generate key word based traffic to a young blog.
I know that with advertising much has to do with brand exposure. But you know what? Most of the indie authors I know don't have that kind of money. It's not like we're Coca-Cola and we can plaster our name in every stadium and tv commercial. There are easier, free ways to make a brand for yourself on the internet. However, if you have the budget, the above listed items I find do help and work almost every time.