Painting an outdoor landscape is one of the most peaceful, rewarding and relaxing things that you can do.
It's not often that you can exercise your creative side and relax, but painting is one of the few things that allows you to do this.
When using watercolours, it's often best to first use a pencil to sketch a brief outline of you subject area.
I usually like to paint a nice view, so I'm often sat quite high up with my paper/canvas laid out in front of me.
Before my brush touches the paper I spend a good five minutes just looking at the landscape.
Most people don't paint what they see, but what they think they see.
This is one of the most basic beginner mistakes, but it is one easily avoided.
After you've sketched the background (and the foreground, in that order) I'd suggest using a flat brush to start painting the sky.
When I paint I do it in 2 phases - the main chunk of it first, then the details.
Before I paint the details I let the first 'coat' dry so I don't end up smudging everything and ruining all of my hard word.
It's easy to get into painting, and you can purchase a beginner's art set extremely cheaply from most art or stationary shops.
Though most of these sets won't have the complete set of tools, it will have enough to get you started, and it'll give you enough of a taste to know if it's something you really like and want to get into.