Purchase a plastic rolling cart the size of a small filing cabinet (preferably with different sized drawers) which will fit under a desk. These carts are available at specialty stores such as The Container Store, as well as discount superstores such as Target and Walmart and local home improvement stores such as The Home Depot.
Lay out all of your art supplies on a table, floor or other flat surface so that you can see everything.
Organize the supplies into groups corresponding to what type of supply they are. For example, group all paints together, brushes, palettes, chalk, pens/pencils, etc.
Create subgroups of each category if there are a lot of items. For example, if you have a lot of paint, divide this group into subgroups based on type of paint (acrylic, oil, spray paint, etc.).
Organize the groups into the drawers of the rolling cart according to size. For a short, shallow drawer, put items such as pens/pencils, erasers, rulers, paintbrushes, etc. For deeper drawers, put larger items such as spray paint cans, bottles of paint and gesso, and stand them upright.
More than one group will often have to fit into one drawer. Use additional containers, such as pencil boxes, old shoe boxes, plastic food containers to place likewise items together. Allow room to add additional items you might purchase in the future.
Label the outside of each drawer. Write the group names of all items in the drawer with a label sticker.
To store the rolling cart out of the way, push it under a table or desk.