During your first training sessions, training pants and a T-shirt will suffice. You may or may not wear socks.
The first thing you need to buy is a black keiko-gi. You can buy these in most budo stores. You may or may not be able to buy tabis. These are the Japanese socks.

As you train longer and longer you can also purchase the various practice weapons such as a bokken, hanbo, bo and the like. Even though we have a some of these practice weapons within the club, for practicing at home it is useful to own this yourself.

And what should definitely not be missing from any training is a good mood and a great willingness to learn.