Watercolor paints, such as the Daniel Smith travel set I have, or Winsor & Newton travel set
+Watercolor brush, such as my Sakura brush with water well
+Several pieces of watercolor paper cut to perhaps 3 x 4 inches
My recommendation is always to have a few, good quality supplies. Having brushes, paints, and papers that behave the way they are meant to keeps your frustration low and your sense of fun high. Also, clutter with too many supplies gets in the way of getting started, and can overwhelm you with too many choices. Start with one thing, and really dive in! Slow drawing and painting are an excellent method for doing this, which is why I practice it and teach it.
Happy creating! xo,