When training in any medium, start with inexpensive materials. All beginners make mistakes so it is best to have materials that are okay to discard. Spiral sketchpads and graphite pencils are available at office supply stores for about $20, and acrylic paints and paint paper can be found at craft stores for about $6 a bottle. Children's craft clay that can be fired in a home oven, costs about $10 and is perfect for aspiring sculptors.
Find a simple object such as a book or a mug to depict in a contour line drawing. These drawings are composed of one continuous line without break. Artists must keep the pen on the page throughout the entire drawing. Begin by observing the object for a few minutes, especially its outer line and silhouette. Refrain from looking at the paper while drawing. Instead concentrate on following the line of the object with your eyes and transferring what you see to the paper. Do not be afraid to make mistakes or to move into the interior of the object to depict other lines. Refrain from shading or attempting to make the picture realistic--the object of this exercise is training in observation skills.
Begin by depicting simple still lives. Arrange geometric shapes such as balls, boxes and cans and place them under a strong light source. Observe the elements and principals of art including composition, shape, form, space, color and texture before beginning. The still life may not be attractive, but drawing simple forms is the base of more complex works. Experiment during this time with shading and mixing colors. Depict the arrangement from four different viewpoints. Concentrate on one part of the arrangement up close or move the light source to change the shadows and note how it changes the composition of the picture.
Studies of the human form train artists in body ratio, composition and movement making later compositions with human forms easier. Completing studies of the human form can be done with wooden artist maquettes available for about $15 at craft stores. Maquettes are models that are about one foot tall with limbs that can be positioned. Begin by sketching the simple shapes of the model's form while moving the model into different positions. When you feel comfortable with the wooden model, move on to depicting people from magazine pictures or ask friends to pose in different ways such as sitting, standing on one leg or stretching. Add details such as clothing, skin and facial expression as technique improves.