There's lots of good advice in this thread. I don't think there's a single point so far that I'd disagree with, but these requests for tips elicit such lengthy lists of answers that I worry newer travelers miss an important point: You don't need to do it perfectly the first time.
Start with what you already know from your experience as an occasional traveler. Anticipate 2-3 things you might want to do differently in the future as you travel more. Pick whatever seems most relevant to you. That might be what seems most important or what's easiest to change. For example, planning how to stick to regular eating and exercise plans while on the road. Make those changes and reevaluate after a few trips. Keep what's working well, drop or change what's not, and always considering learning another new trick based on experience-- your own or someone else's. In time you'll be a pro.