Build a Great App but Don't Forget Marketing
"Whatever type of product you decide to build, you need to make sure it’s something you’re interested in, something you care deeply about. Don't build it if you're not passionate about the idea or possibilities it holds, don't build it because you think there's a gap in the market and it’ll make you millions, because it won’t.
Build it for the fun of doing it, build it because you’re passionate about making great products, build it because you enjoy the process, build it for any other reason than to get rich.
Making a living from building and selling apps is bloody hard work. Most apps fail to make a return on the cost of development, let alone sustain a lifestyle. The chance of failure is very high and the odds stacked against you. If you followed your passion and your app does fail, at least you’ll have shipped something that you can be proud of."