Other Supplies
Palettes
I use a Tom Lynch Porcelain Palette. However, you may use something as simple as a ceramic plate. There are many palettes on the market, it's just the matter of finding one that suits you.
Painting Supports
To prevent your watercolor paper from buckling, you'll need to support it. I use tape to attach paper to a wooden board. The support prevents the paper from developing wrinkles when you apply water and it provides a stable surface for painting. I also place my wooden board on an easel because it's easier to position the paper at an angle that's comfortable for painting. It all depends on what you're comfortable with. You may start out on the kitchen table; I did.