Don't sweat the stuff you can't control. Life is much too short to be angry & annoyed all the time. Just take a deep breath and remind yourself that it could be worse.
Wake up early
Rise at sunrise to have the best attractions all to yourself while avoiding crowds. It's also a magical time for photos due to soft diffused light, and usually easier to interact with locals. Honest hardworking people wake up early; touts, scammers, and criminals sleep in.
Laugh at yourself
You will definitely look like a fool many times when travelling to new places. Rather than get embarrassed, laugh at yourself. Don't be afraid to screw up, and don't take life so seriously.
Keep extra cash
Cash is king around the world. To cover your need in an emergency, make sure to keep some in a few different places. If you lose your wallet, your card stops working, or the ATMs run out of money, you'll be glad you did.
Meet local people
Make it a point to avoid other travelers from time to time and start conversations with local people. Basic English is spoken widely all over the world, so it's easier to communicate with them than you might think. Learn from those who live in the country you're visiting. People enrich your travels more than sights do.
Observe daily life
If you really want to get a feel for the pulse of a place, I recommend spending a few hours sitting in a park or on a busy street corner by yourself just watching day to day life happen in front of you. Slow down your thoughts and pay close attention to the details around you: the smells, the colours, human interactions, and sounds. It's a kind of meditation and you'll see stuff you never noticed before.
Keep both digital and physical copies of your passport, visas, health insurance card and important phone numbers ready to go in case of an emergency. Backup your files & photos on an external hard drive as well as online if possible
Take lots of photos
You may only see these places & meet these people once in your lifetime. Remember them forever with plenty of photos. Don't worry about looking like a "tourist". Great photos are the ultimate souvenir.
Don't be afraid
The world is not nearly as dangerous as the media makes it out to be. Keep an eye out for sketchy situations but don't let that be the focus of your whole trip. Use common sense and you'll be ok. Most people are friendly, trustworthy, generous, and willing to help you out.
Get lost on purpose
If you want to see the parts of town where real people live & work, you need to go visit them. The best way to do this is on foot — without knowing where you're going. Write down the name of your hotel so you can catch a taxi back if needed, then just pick a direction and start walking. Don't worry too much about stumbling into dangerous neighborhoods either, as locals will generally warn you before you get that far.
Eat local food
Taste a bit of everything when you travel, especially if you don't know what it is. Ask local people for recommendations. Eat street food from vendors with big lines out front. Don't be scared of the food.
Please don't try to explore 5 countries in just 10 days. You'll miss a lot if you only spend a day in a city or town. All the good stuff happens when you really take the time to explore an area. I can honestly say that NONE of your best travel experience happen within the first few days of arriving somewhere. Spend more time in fewer places for maximum enjoyment.
Treat your body well
When you're travelling from place to place it's difficult to maintain a workout routine, and many of us slow up. Remember to be nice to your body. Get enough sleep, stay hydrated, eat healthy, use sunscreen, and exercise often
Stay in touch
Remember to call your family & friends from time to time. Travel isn't lonely, far from it. You constantly meet other people. But many of those relationships are fleeting. So maintaining a strong connection with the people who know you best is important.
Most people who wait to travel the world never do. It's a big, beautiful, exciting, and fascinating world out there. Explore some of it now, rather than later.