Let's start by listing the 5 main areas you need to understand.
1.
Mediums

• Since you're reading this, I'll take it you've been drawing and painting for some time.
  So, looking at your artwork to date, you already know that you prefer charcoal or watercolours on paper, acrylics on board or oils on canvas.
  All are acceptable to galleries and popular with the public.
  The one you choose is called your 'medium.
  ' It defines you in the first sense, as, for example, a draughtsman in black and white, a painter in watercolours, oils, pastels or other.
  

2.
Materials

• If you choose to work on paper, you'll need to learn about paper qualities.
  For drawing, you can choose between pencils, charcoal, pastels or crayons.
  Drawing is the basis of all visual art.
  

Pencil is the medium we all start with as children.
It remains the one relied upon by artists to create the sketches that become great architecture and sculptures.
Charcoal comes in two forms: compressed as a pencil or in sticks made from vines in various thicknesses.
Sticks are the professional artist's preferred form.
Pastels are a medium composed of pure pigment.
Artist grade pastel sticks are unsullied by addition of any fillers or glues.
A hardier form is known as Conte.
Crayons are a waxy stick of pigment and binders which come in many grades.
They are popular with children and fun for hobbyists but rarely acceptable to galleries or collectors.
Papers are a subject in their own right.
You'll need to study their qualities and learn how to prepare them for the different mediums listed above.
3.
Techniques

• Your choice of medium and materials influences the painting techniques you adopt.
  

Working in watercolour, requires great finesse in preparing the papers and handling the paint.
Confidence is vital to your brush-strokes.
This is a Master's medium and not for the faint-hearted.
Painting on boards, with acrylics or even with oils, allows you to lay on a heavy impasto with the knife.
The results can be spectacular and crowd-pleasing.
Painting in oils on canvas is the most forgiving of mediums.
It has a proven history of longevity and can withstand the rigours of restoration better than any other.
Oil paintings on canvas attract serious collectors and achieve high prices in private galleries and auction houses.
4.
Styles

• Each medium you choose suggests a style or way of using it.
  Let your materials speak and your style will begin to develop itself as you work.
  

The main thing to avoid is fashion.
By its nature, fashion is fleeting and fickle.
5.
Subject Matter

• As with every other aspect of your art, subject matter grows from your personal preferences.
  Here's a simple way to discover your true direction as an artist.
  

Gather all the work you've produced to date.
Spread it out on the largest table or clear floor space available to you.
Invite a trusted, honest friend to pick out the pieces that seem most 'you.
' The selections will have some element in common.