Do your ground work, try to ensure your idea is viable. Be objective, which is hard when you are passionaite about what you are doing. Cover the downside, make sure to only invest what you can afford to lose. Sometimes following your dreams is worth more than the money in the bank.

Not sure if it's my "best" advice, but I'd definitely say one of them is just to get started already! The sooner you start, the sooner you fail and the closer you are to success.