Any lessons learned that you want to share? As the owner of a very small consultancy shop I know it's very hard to extract generalized advice from your own failures, but still...
* Find a niche market where there is a need and the prospects aren't broke. Eg, they have money to spend for the potential of ROI with your product.
* Break your revenue goal into concrete building blocks. If you need $x/year to make this a profitable venture, how many customers do you need?
* If you need a lot of customers (IMO, > 25) you need to think about both marketing and making your product and making it possible for them to self-service. Eg, driving inbound so you don't have to rely so much on outbound.
* Right down your goal and make a plan to achieve it. Does that mean emailing / calling prospects? How many per day? How many trials does it take to convert one customer? These are simple metrics which will eventually help make your revenue "predictable." Great books on that topic.
* Sales is #1 priority. SV is hyperfocused on brilliant engineers. In bootstrapping, it's all about money. I'd spend more on a great salesperson than an engineer.
* Make yourself uncomfortable. Don't like cold calling? Cold call anyway. You'll get good (or at the very least not half bad) at everything.
* Take care of yourself. You are your own vehicle to success. Your mind and body are business partners. Your bad habits can hinder you severely. 9-5 employees can come to work hungover every day and probably get by fine - but an entrepreneur can't.
* If something isn't working, change it. If something's working, do more of it. That includes pivoting product, market, etc.
* Don't get too elated or depressed. There can be incredible highs and crushing lows. Failure is a teacher but success is a better teacher.
* Be humble. Recognize that you're an idiot and that you don't know shit, even when you think you know shit. It's how you keep your mind open to learning new things. Your own ego can be a roadblock to success.
* Learn to delegate. When you start out you'll do everything — but eventually you will find you have low-level tasks which, if offloaded, would make you far more productive. That's when it's time to hire. Resist the urge to just do it yourself. Your ultimate goal is that you become the brain of the company and you delegate the physical work to the staff you've built.
There's a lot more but those are the ones I could rattle off.