I've found practicing outdoors a great way to improve my art, learn about perspective, tonal values, how to simplify the scene in front of you, etc.
Working on location, or plein air as the French call it, is a lot of fun. It also takes getting used to. First you identify a nice spot which you can paint or sketch. Then to lay out your portable seat, paints, water, etc and then onto putting pen or pencil to paper. There are people around who will come and look at your work in progress, ask thousand questions, kids who have no compunction in giving their candid opinion of the art you're creating.
If you have little time to spare then carrying just a sketchbook and a few pens is good enough. If you have a lot of time then attempt a fullblown painting. As with any other skill this takes time to get good at, and can be frustrating initially, trying to juggle the paper, palette, brush, in the space you have.
Here are a few of my recent outdoors artworks: