Let me get one thing straight: transferring schools was the right choice for me in the long-run and I don't have any regrets about it. This is true for many people out there. That being said, there's a lot that nobody told me about transferring and I wish that they had.
1. You're going to start sounding a lot like Phoebe from "The Magic Schoolbus."
As wonderful as your new school may be, you're going to find yourself reminiscing about the way things were at the school you left. From the different traditions to class sizes, to the overall climate. "We didn't do this at my old school" is going to become one of your most-used phrases.
2. You're about to feel attacked by questions.
The minute you tell someone you're a transfer student, you're going to be met with a million and one questions. Where did you transfer from? Why did you leave? Do you miss it? Do you like it better here or there? How different is it? Are classes harder here? Was it because of money? Did you want to be closer/farther away from home? It's going to sound an awful lot like a job interview, but be patient.
3. The FOMO is real.
If you stay friends with people from your old school, you're going to be seeing all the social media posts about the goings-on there. From old traditions to events you wish you could go to, to club meetings you used to love, to theater productions you know you would have auditioned for, it can be bittersweet to see your old squad doing all of those things without you. Don't let the old interfere with all of the great things you get to do now.
4. Transferring credits is the 10th circle of hell...
Some of your credits won't transfer, or they won't transfer for the same requirements as your old school. What counted as a science class in one school may not count as such in your new one. It may happen that you'll have to take classes over. And depending on how many credits transfer, you may have to take winter and summer classes to play catch up. The sooner you come to terms with the fact that you took some classes "for fun," the better off you'll be.
5. ...and getting in contact with schools is the 11th.
It's impossible to get in touch with people who work in universities. Especially if you need them to get back to you in a timely manner. You're going to be on hold for hours on end only to be told no one can help you. This is especially true when discussing issues of financial aid. It's annoying, but you will have to be persistent or you will not get anywhere.
Whatever your reasons are for transferring, and despite all of the issues there are with it: know that it's all going to be alright. You're going to have a great time at your new university, and are going to make so many amazing new memories.