I never dormed but a lot of my friends (mostly guys) were in triples their freshman year. I can't really speak from experience but I can describe some things that have happened to my friends. They all survived and most became pretty close friends with their roommates after freshman year.
Some of this is actually pretty general advice although you can probably squeak by a while in a double not really caring about some of this.
First, is either roommate planning on rushing? You might end up in a double if one of them joins Greek life. My friend was still paying for a triple while living with one other roommate all year.
Second, have some sort of system with your roommates. It's going to get cramped - even some people complain doubles are tiny from what they're used to. Set down rules/what people are used to (ie. don't let people sit on my bed with their shoes on, yes you can have some of my ramen when I'm not here but let me know please). Communication is key, especially with roommates.
Get to know your roommates. You're living with them for however long you guys stay in that room - whether a week, a quarter, the entire year, or maybe you all love each other so much that you're going to room in an apartment together next year. Who knows? It might feel kind of awkward "thrown" into a room with people you might not know. There's 3 ways your relationship can go - you become good friends, you hate each other, or they just "exist". Of course, this requires two sides to mutually share the want to become friends. If they're really quiet and don't go out much or even talk a lot, ask them if they want to tag along if you're headed out to lunch. They'll remember (probably..).
Remember that although you live in a dorm, you don't need to stay there all the time. It'll get stuffy, maybe too warm, and maybe you want to get away from your roommates once in a while. Go out with friends. Study elsewhere if you can't concentrate in your room.