Observations from that time:
1. Clearly lay out your goals and timeline in documentation that's accessible to the whole company. Even if they change later (and they will), this gives you a common understanding to work from.
2. Religiously adhere to a work management system. It doesn't matter if it's GitHub issues, Trello, Jira, or whatever, but all work should be tracked and tracked in a central location. Email does not count.
3. Stay as small as you can for as long as you can.
4. Perfect is the enemy of done.
5. Find a small group of people that you trust that are willing to be part-time testers occasionally. Feedback from people who don't know every mechanic is invaluable.
6. Marketing is important, but only once you have something _to_ market. Blog posts about how great your systems are going to be are not as impressive as blog posts (with screenshots) about how great your systems _are_.
7. Be very, very careful about the licenses attached to software and libraries that you're using. There might be language in there that will cause major headaches for you, especially if your game becomes successful.
8. Keep dev costs as low as possible as long as possible if this is your first title.
9. Remember your mental health. Take actual breaks where you don't even _think_ of video games for several hours. Spend time with friends and family. This will keep you sane and productive.