I will offer my watercolour knowledge. :P

Materials:
I like to use the paints that come in a cake form. Yarka is the brand I use. This way there is less waste and the paints are kept neatly in one place. Tube watercolours work as well, but there is often more waste, even though the paint can be reconstituted with each use. I believe they're slightly more costly in the long run as well, but I'm not positive. Personally, for tube paints, I prefer Winsor-Newton. I've had most of these since I was in middle school. :O

As for paper, there's hot pressed or cold pressed. Cold pressed allows for more time to work with the paint as you can bring up the colours easily with water over and over. The paper has more texture as well. The paints flow better over the surface and you can get some interesting effects that way. Hot pressed is very smooth, almost like bristol board, and sucks up the paint much faster. The paint is less readily brought up with water once it's down, though you have more control over the pigments as they don't flow quite as much over the paper. (I'm not sure I'm making any sense!! haha. sorry :S )

Brushes are tough. You need to find something that you feel comfortable with. I like slightly firmer brushes with more spring to them. For watercolours you'll want soft brushes though, as opposed to the rougher brushes used for acrylic. You can find both natural fiber and synthetic fiber brushes. It really all depends on what effects you want in the painting. I use both, though primarily I use synthetic. Sometimes these are slightly cheaper.

Tips:
I can't think of any tips at the moment really. ha.
um. I like to use watercolours in conjunction with an inked drawing or pencil drawing. Sometimes I lift up the lead a bit, other times I shade with the pencil and achieve a muddy sort of effect. I've also used watercolour over a coloured pencil drawing, which is interesting as the oils in the coloured pencils repell the watercolours.

erm. I dunno. If you have any questions, feel free to ask ;P

Hope this is somewhat helpful!

Quite helpful, thanks! You actually did make sense, so that was really useful information.
Do you ever have a problem with painting and inked drawing and having the pen ink run? Do you think using the right paper will help stop that?

No problem!

What type of pen are you using?
I usually ink with either microns, copics, or india ink with a crow quill pen. all of these should be waterproof once dry. (at least, I haven't had any problems with them running...)