A random list of thoughts from my last few years of fighting in the trenches of technology and startups.
Avoid burnout at all costs.
I am only starting to realize how burnt out from work I was after I left Ask/IACI/Bloglines in 2008. I didn't want to work. I believe it took 6 months before I was even ready to really do anything hard again. I took the stress at Ask and just worked more, worried about issues more, and just tried to do more. Take time off. Relax. Watch Glee or True Blood. It might seem silly when you are in the heat of a production crisis at 4am, and you'll still want to be up at 4am fixing the problem, but make sure you arrange for a time to relax and decompress. The consequences and feelings of being burnt out far outweigh that lost hour from watching Lady GaGa or reading that new sci-fi book.
Always be learning.
We work in technology, and it is always changing. Every week there is some great new hot project on github or spreading around twitter. Take the time to check it out one night. Working for a startup like Cloudkick, some weeks are insane, but if I haven't learned anything, something is wrong. It doesn't have to be technology; But not taking the time to check something out has meant for me I'm approaching burning out.
It's all about the People
Find people you enjoy working with. Avoid poisonous people, both in your work environment and in any open source projects you want to be involved with. Life is too short to be fighting with people over a personality conflict or stupid bikesheds on the internet.
I hate issue trackers. I hate organization tools. My mind just doesn't work that way. But, I've found using Google Tasks inside gmail is just lightweight enough to replace a ~/TODO file. But you need something; A notepad, a ~/TODO file, or anything, but keep track of things other people are depending on you to finish. No one works in isolation.
Be aware of your Habits
For the last couple years, I've been on a bad streak of drinking tons of Diet Coke. Every time I'd get up, I'd grab another Diet Coke. I have stopped drinking diet coke for about 2 months, replacing it with water, and definitely feel better. And no caffeine replacement like Coffee. Is it just a placebo effect? Hard to know, but my point is be aware of the habits you get into when you are so hyper-focused on a project for weeks straight.