It is always overwhelming who much you mislead yourself into thinking you know what people have in their minds. Even now, as I have started many companies and have been consulting startups and corporates for years, I still step into this trap from time to time. Therefore my top advice is about staying open minded:
1. Talk to you CUSTOMERS before you think about websites, pricing schemes, bureaucracy, corporate identity and all that sideshow business. You will be surprised about how much people don't care about the solution in your mind. And you will be surprised about all their real pains in the ass that you can solve much more easily. The customer is the customer :-)
2. Keep things MANUAL and tinkered as long as you can. This is especially true if you come from a corporate background and are used to high-gloss appearance and processes. Being overly concerned about automated solutions and polished brochures makes you inflexible way too early. If and only if things get out of hand, go for more professional solutions. If you provide real value, nobody cares about a crappy business card. Unless you are in the printing business, of course :-)
3. COLLABORATE, collaborate, collaborate. Nobody is going to steal your idea. So don't be afraid to talk to other people. Get out of your own silo and go for the next level. There's always a bigger idea. Of course, there's also always a bigger fish. But that's another thing, not to worry about. The bigger the fish, the slower they are. It is all about constant innovation. Staying open and flexible will keep you in the game!