There are several types of shelving to choose from. Click on the links below for variations.

When choosing wood for the shelves remember some materials will be stronger than others. (See section on wood) e.g. MDF tends to eventually sag if you put heavy things on unless you support it along its length.
For shelves with brackets, as a rough rule of thumb you should aim for a bracket every 600mm.
At the end of the shelf should normally hang approx. 100mm beyond the bracket.

Fixed shelves with brackets
Adjustable slotted shelving with u-brackets
Fitting shelves in alcoves with wooden battens
Fitting extra shelves in a wardrobe or cupboard
Floating shelving