For extended life and playability, the correct storage of your vinyl recordings is of paramount importance.
Some of the issues to consider for the proper storage of discs are temperature and humidity, dirt and dust, improper stacking, excessive pressure and weight.
Although not always possible, an average temperature of 65-70 degrees Fahrenheit or 21 degrees Celsius should be maintained. Plus a constant humidity level of 45-50% is highly recommended. Any extreme changes in temperature & humidity could have a devastating effect on the life expectancy of your vinyl recordings.
Special attention should also be placed on sunlight and on sources of heat such as radiators, vents, and artifical lighting. Also beware of high humidity and water. This will cause mould to grow on the album jackets and within the inner sleeves causing unrepairable damage.
An an ideal situation enclose your recordings in relatively airtight surroundings, such as a cabinet with doors, or sealable boxes. Don't be afraid to lightly vacuum the area surrounding your records. Replace dirty and mouldy record jackets and inner sleeves to avoid further damage to the discs. Do not store your collection in or around smokey or cooking areas. Smoke and cooking greases easily adhere to records and their jackets.
Definitely avoid the storing of recordings on their sides or flat! Always maintain records in a vertical position. It's also advisable to remove the original manufacturers wrapping from records. These wraps will shrink over time, eventually warping the jacket and it's contents. Replace this "shrink wrap" with high density polyethylene sleeves. Additionally, As with most objects (including humans!), time will eventually take it's toll but if you follow just a few of these simple steps, you will help to extend the life of your vinyl collection to enjoy for years to come.
You want to store vinyl upright, ideally dead straight (not at an angle). If you store them flat, there will be all kinds of pressures on them that can cause them to sag and warp and not play properly any more. Put them upright on a nice flat, strong shelf, with bookends at either end to keep them straight, or store them in something like milk crates, packed tight enough that they won't move around.