Here's me teaching watercolor painting at PSU, University Park in '13.  I started teaching in '94 and retired in '15.

Above that photo is a list of some lessons on drawing and watercoloring I used to teach my art students.  These lessons contain rules that are simple and most contain exercises that are easy to do.  Yet they can have a great impact on your art.  Try them.

As an art teacher over some 20 years, here's what I've learned . . .

Focus — convey something in an artwork.  Could be simple like an object, to complicated like a feeling.

Purpose — only use elements like media, hue, value, composition, etc., which further my focus.

Unity — combine elements so my focus will be a viewer's first impression.

Pencil — Two Blackwing pencils.  One Blackwing with a a sharp point and a second one with a blunt point.  Other pencil brands are good as long as they are 4B, the only grade I use.  Pencil extenders.  Canson pure-white drawing paper, a white eraser, a kneaded eraser, small tortillion for eyes, and drawing boards (different sizes) onto which I tape my paper and reference photo.

Watercolor — I use transparent watercolors by Schmincke and Daler-Rowney (pans not tubes), round sable brushes size #3 to #12, Arches 140 lb cold-press paper, masking tape (to tape down the paper on all sides since I don't pre-stretch the paper), small oil-paint brush for removing paint, latex masking fluid (I apply masking with a child's nylon watercolor brush), various plastic pallettes, an old t-shirt rag, and painting boards (different sizes) onto which I tape my paper and reference photo.