Paula asked which colors I chose for my limited palette. This one is modeled after one of Cathy Johnson's, including the altered paintbox itself which is a Koi painbox. I removed the original contents, leaving only the little waterbrush, and added full and half pans into which I squeezed Transparent Yellow, Quin. Red, Winsor Blue, Paynes Gray, Burnt Sienna and Raw Sienna. There are 2 watercolor brushes, a #1 liner and a 1/4" flat with sharpened ends for scratching back, plus a sponge, pencil and sharpener, and molded eraser. You can see by my dirty palette that I reused dried puddles and I don't often clean my colors, preferring to dip into whatever is there that's useable.
Part of the looseness is due to the finish on the moleskine pages. Mine is the sketchbook with the slightly yellow and stiff pages, and unless I wipe the page down with a moist towel to remove the sizing the pages slightly repel water. I like the look but watercolor purists rail against the paper and use other books. I chose moleskine because of the overall quality of the book. It stands up to just about any abuse and since I carry this book in my purse everywhere I go I need the strong structure.
It doesn't matter which colors you choose for your limited palette as long as you've experimented with them enough to know that you can mix satisfactory colors... good greens, bright purples and magentas, and orange. If the yellow, red, and blue you already own as long as they mix to form beautiful secondary and tertiary colors. And of course, be creative with color, using any color to represent any object, as long as the value is right. I could make my daytime sky pink and my water purple, as long as the pink is light and the purple is dark.
And BTW, the link to Cathy Johnson is to her Art Tips page where there is scads of information on how to paint with watercolor. She's the master!