Always be learning - Teach yourself new techniques. Expose yourself to different ways of thinking. It doesn’t have to be about games either. An artist I know learned how to build Arduino electronics and started joining us programmers for lunch to ask great questions. He invited us to join the artist's weekly nude drawing class (but I’m not sure any of us took him up on it).
Pace yourself - Crunch is inevitable, but lots of research has shown that beyond several weeks, productivity can drop below that of normal hours. It can take courage to shut down the studio for a weekend after several weeks of crunch, but it is worth it.
Micromanage less - Coach and encourage your developers to solve problems on their own. When they come to you with a problem, ask “what have you tried” instead of providing the solution. When you see a problem they don’t, ask them if they see the problem instead of telling them what to fix.
Grow cross-discipline communication - Problem solve across disciplines instead of handing off design docs. Find ways to communicate more. Steve Jobs famously designed the Pixar building to “force more interactions” between disciplines. Look at ways of generating conversations through cross-discipline brown bag lunch sessions or even trying different seating arrangements.
Play your own games often and early - Many mechanics that make games great didn’t appear in the original design document, but emerged mid-development from the team. Many of my best memories of game development come from end of day sessions playing our game and talking about improvements over a beer. The earlier you can enjoy even a core mechanic or two, running with placeholder assets, the more engaged the team will be with the game.
Invest in people - Game development is craftsmanship, not mass production. Traditional craftsmanship requires years of apprenticeship before an effective level of skill is reached. Assume people are at different levels of skill and help them grow where they need to. Sure, they might take their new skills you invested in and go someplace else, but a studio that respects people enough to invest in them usually has great retention rates.
Enjoy each other - Do things outside of work. Don't let the schedule and stress kill relationships. Decades from now, when you are reflecting on your career, you’ll remember the people you worked with more than the games you made.