What we did was ensure we could have a story behind the product we were building. From the start we knew exactly what angles we can approach the press with for our app. In fact the timing was perfect for us and we managed to get a lot of good press (AllThingsD, CNET etc).
Unless you have the perfect product don't expect anything but a spike in downloads/visitors to your product.
For me it has been an excellent learning process and every time I release something I get better and better at it.