When you travel, you’re in the sun more than most people thanks to months of island hopping and beach time, and entire days spent outside exploring. Wear sunscreen every single day, regardless of the weather and temperature, because you really don’t want your trip of a lifetime to result in skin cancer. Plus, it prevents premature ageing! I wear sunscreen every day, even in the middle of winter.
This may sound corny, but in an age where travel is stressful and everyone is grumpy, you'll find you go a lot farther if you lead with a smile. I've gotten free First Class upgrades, room upgrades, even free products and services just because I was polite, courteous and cheery. Sometimes, I have to fake it -- after all, business travel is HARD, but you'll find it's easier on you and on others if you lead with kindness.
If you're staying in a hotel, call in advance to see if laundry services are available and how much they cost. Travelers staying in properties without laundry facilities or taking cruises—cruise lines are notorious for charging an arm and a pant leg for laundry services—can wash clothes in sinks and hang them to dry. I always make sure to pack a travel-size packet of laundry detergent and a sink stopper to clean my clothes on the road—it's my secret for fitting everything in a carry-on bag. Portable laundry-drying lines that attach to showers via suction cups are also a good choice; you can find them at many travel-supply stores.