The main needs for successful wine storage can be summed up as follows:
It should be easy to find any wine, and to discover wines of the same sort in adjacent racks. Use labels or a logging system.
Wine once stored should be left alone. Therefore it should not be necessary to move one bottle or case to get at another. Avoid rigid racking systems that cannot be altered to cope with changes.
Angle Of Storage
Wine must be stored horizontally, to keep the cork moist. Some collectors fit racks and bins with a very gentle backwards slope to encourage deposits to form near the base of the bottle, while the cork stays moist. Place labels uppermost, so that the deposit will then form on the opposite side of the bottle.
Freedom From Vibration
The kind of harsh vibration caused by domestic machinery, or a nearby road, can harm wine. Racks will insulate the bottles to some extent.
Air circulation is essential, though this may clash with the need to keep temperature low. A true cellar should have air bricks or ventilators allowing air from the outside to enter and circulate. These can be blocked in very cold or very warm weather. If the cellar has north- and south-facing walls, place ventilators as low as possible on the north side, and high up on the south side. This utilizes the natural flow of air, with warm air being extracted from the upper ventilator by the convection effect of the warm south-facing wall, and cool air from the north side flowing in to replace it.
Ideally, relative humidity should be 75-80%. Excess humidity rots labels, cardboard boxes and (eventually) corks; but if humidity is too low, corks may dry out.
You can raise humidity by covering the floor with a layer of gravel and watering it.
Dehumidifiers can be used to extract excess moisture from the air, but these are expensive and only worth considering in large cellars. Deal with excess humidity in small cellars through drainage and improved ventilation, and by sealing off moisture sources such as very damp walls. Labels can come unstuck in a damp cellar: an elastic band will stop a special bottle from becoming anonymous.
If possible, clean the cellar thoroughly before storing any wine in it. Use a disinfectant, preferably without a scent, to kill mould, insects and other organic life. Then paint the walls with a porous paint such as whitewash: it is not a good idea to seal brick or stone walls as this inhibits natural ventilation and humidity control, and can cause condensation.