1. Plan Too Much
As a new solo traveler it can be tempting to plan every minute of your adventure in advance. But here's the thing, when solo traveling, it's usually way more fun if you can be flexible. Traveling without a strict itinerary can allow you to adapt your plans when you meet other travelers. Plus you might meet other travelers and decide that you want to spend a few days with them. Stay open.
2. Don't Stay in Hostels
When I first started traveling I thought hostels were dirty, grimy communal rooms, jam-packed with bunk beds for early twenties, recent college grads who only want a place to crash on after a long night of partying. But I was wrong. There are some really amazing hostels out there. And it's one of the easiest ways to meet fellow travelers. Just be sure to read reviews and if it's your first time, make sure the hostel you're staying in has at least 200 reviews so you can be sure you're getting a good place.
3. Be Afraid
Sometimes venturing out on your first solo trip can be scary. But being limited by those fears isn't any fun. You're traveling solo to have fun, and conquer fears. I'm not saying be reckless. So ask yourself, if you fear rational? You don't want to be afraid of your own shadow, but you don't want to be careless either.
4. Fall for Scams
Any destination that draws a lot of tourists is likely also going to have a decent number of scams. Don't be a target. Read up on common travel scams before you go so you can be prepared. Don't allow this to scare you or make you super defensive, but you also don't want to be unaware of basic cons that happen. You'll want to have a sense of the appropriate prices of cab rides, or street food before you arrive.
5. Bring Too Much Stuff & The Wrong Stuff
Before I left on my first solo trip I bought pickpocket-proof pants, and was even considering a slash-proof backpack. In reality, neither were really essential for my trip. In fact a simple reusable bottle and some reusable cutlery would have been more helpful and a lot cheaper too. So pack lightly, especially if you're traveling to a country that has a lower cost of living than your home country. That way you can buy anything that you happen to need once you get there. And then you'll also have unique items to take home with you.