This will be nothing new to most folks but, what the heck! I have  enjoyed the good fortune of working at one level or another with far too many entrepreneurs to count. Frankly, the best were those who had failed a few times but had learned from each failure and employed the lessons learned in those failures. I can tell you that nearly all over estimated revenue in the early going, even more missed on the selling costs and the real failures were those that didn't throw themselves into the sales and marketing aspects of the business. Oh of course the product has to be developed and produced but you cannot win with inadequate sales so  bury yourselves in marketing activities and then produce the product to meet the customer needs. If you'll do that and not waste money nor fear hard work, then your small business has a chance of caring for you over the long haul.
Simple as this all might seem, I'll bet that over half the failing businesses that I've advised forgot these simple truths long enough to drown in fear and self pity when just a little focused effort could have gotten them over the hump! Simple as that, as is much of life! So go enjoy the fruits of a labor well invested.
Aloha!