Just a Reminder...
Before we jump into this - as with any other animal, it is good to familiarize yourself with their needs before adopting them for the first time. You will want to know what types and sizes of housing they should be provided with (and what kinds of toys will be most beneficial for them), what to and what not to feed them, and the types of treats and other foods that should be supplemented into their diets. While this article will give you an overview of what to expect with a rat, you should do much more research than I can provide here.
One of your first decisions to make is "What will my rat(s) live in?" Of course, there are hundreds of cages on the market today, but this task is relatively simple. You can also opt to make your own, which I will cover in a moment. But before anything else, you should first know how many rats you will be putting together, or how many cages of rats you will want. If you have a