My tip for the day: keep writing. I just got my royalty statements for last month/last quarter, and they supported what pro writers say all along: when you release a new book (or have a big promo push on one), inevitably your sales for the others go up. Yes, it has happened for me every time. And this isn't just true for e-books or print releases; I've found the sales cross over. My One Night in Boston ebook sales have been high for a few months now (thanks to Samhain's Amazon Kindle Freebie back in April), but I noticed for the first time that the print sales of that book were also up in the months following, as well as ebooks and print copies of my other titles. Looks like those who buy in both formats will seek out their favorite from you.
Sidenote: this seems to be true even if your reviews aren't what you hoped. As I mentioned a while ago, the Amazon reviews for One Night in Boston hover around a 2.5/5 - certainly not stellar. Despite that, sales weren't incredibly hurt by those reviews. So develop a thick skin and take reader reviews with a grain of salt (or don't read them at all, which is what I've taken to doing, honestly).
So if you're a first-time author and are worried that sales are low, yes, work on promo and establishing a name for yourself especially online - but also keep writing. You'll find your royalty profits grow with every release you have.