Rule #2: Fix whatever you complain about most
We all fall into the trap of complaining. When it comes to complaints, you have one of two choices. You can continue to complain and get more and more frustrated - or you can fix it.
Early in my career, I was involved with some of the early software companies here in the valley. One of the biggest complains we had was around duplicating the disks (yes ... 5 1/4" floppies) that would go into our packaging. Back in those days, we would hire high school kids to set in front of a PC and duplicate by hand. The problem was that kids would be kids. We would end up with blank disks (oops - forgot to stick than one in) to disks with prank software (remember: this was before virus scanning tools).
It seems that others had the same complaints and proposed the idea of creating an automatic disk duplicator. The company was Mountain Computer (Scotts Valley, CA) and the product was ImageCopier (Code Name: McKinley).
I was so convinced that this was a complaint that I could and should fix, I signed up to be responsible for writing the software (as a contractor) while others designed the hardware. In record time, we developed something that was a direct fix to the biggest frustrations for software companies .. the product went on to be the leading duplicator for many years.
My advice: fix what drives you (or your customers) crazy.