I've flown alone before, many a time. The first time I flew alone was international and it was a disaster lol (luggage got left behind in NYC, I was in Italy and didn't get it for a week. My phone was working domestic and I needed it to be international, I was 2 hours late for my chauffer to the port for the boat and couldn't call my boyfriend's parents. I was hysterically crying and don't speak italian..haha) :D, the second time, I was flying alone to a country where nobody was there to meet me so I had to figure everything out on my own haha. Actually, all the times I've flown alone, I was flying internationally...
It's not NEARLY as scary as you might think. The first time you might be nervous, but that's ok! Afterwards, you feel like a boss and that you can take on anything! My tips:
*Give yourself PLENTY of time to get everywhere. Plenty of time at your original airport, plenty of time at your layover, plenty of time to do any and everything. The more time you have, the less you'll be flustered about making deadlines and matching flights if something DOES go wrong.
*Have an initial water bottle and snack. Airport food can be PRICEY, and if your flight doesn't come with on-board meal you might get really hungry. I always pack a water bottle and nuts to hold me over as much as I can, although I have to drink the bottle before I can go through security (yes, I give myself THAT much time lol)..
*Wear easy slip-on/slip-off clothes, but I like simple layers. You might get hot/cold depending on if the temps for your destination are different, so it's nice to be able to layer a bit if you need to!
*Bring a book and charge up your devices! Nothing's worse than trying to sneakily charge your iphone on a stereo dock in an electronics store (Yes, my friends did that once. The manager was totally cool with it. Personally, I thought it was hilarious)..
*Write out as much as your can about your journey and give it to somebody so in case something happens, they'll know where you're supposed to be. Have a copy for yourself and research as much as you can (look at maps of your airports/terminals, what food/shops might be there, what airlines are near yours, times of arrivals/departures, plane #s). The more info you have going in, the easier it is to find things!
Good luck and have a blast! I love to fly now, whereas it used to TERRIFY me!