Thinking about traveling with paints? If you have a choice, go light. When I started taking my paints travelling, I took a collection of fifty or so watercolor tubes, a couple dozen brushes and several blocks paper. After a while I noticed that getting a painting going was such a production that it didn't happen very often. When I trimmed down my kit, I started painting everywhere, even at outdoor restaurants. Winsor & Newton makes tiny sets of watercolors in a field kit that fits into the palm of the hand. They have anywhere from 6 to 24 color pans, and range in price from fifty to a hundred dollars. The set uses professional watercolor blocks for the color, so the results are vibrant and the color long lasting. It also has a little brush that pulls apart like a custom-made pool cue. Cute, but unless you are a child, a cramp-fest for the hand, so a better brush is a requirement. Read on.
When traveling—especially when flying— I tend to pack Winsor & Newton Watercolor paper blocks. No messy paper stretching or warping of unstretched paper, because you paint right on the block. Use a kitchen knife when the painting is dry to peel the painting off the block and you're ready for the next. It's handy because you can store your finished paintings with the block until you're done. Watercolor blocks are available both hot and cold press in sizes from postcard to really big. I'd recommend at least one professional watercolor brush, Winsor and Newton 7 series sable will get you the best results. Another tricky thing I travel with is an inflatable water bucket for watercolor. It blows up like a kid's pool toy, and holds a couple of cups of water. With the watercolor set, an extra brush or two, your blow up bucket and a postcard-sized watercolor block, you can travel anywhere and watercolor wherever you want. Just ask for an extra glass of water at the restaurant.
If you are more serious, you can purchase a watercolor plein air easel. Any professional art supply store should have some to choose from. The watercolor and oil easels are different, so make sure you get a watercolor easel. Make sure you know how heavy the thing is empty and that you are comfortable carrying that much weight—plus paints and brushes—into the field. There are half boxes, if you don't want the full weight. There are many brands on the market. The cheapest is probably Richeson, a student brand. I have one, and I've been very happy with it.