Attics can be extremely hot in the heat of summer, while basements can be very damp- which is best? Neither. A good rule of thumb is if the area is comfortable enough to sleep, it’s acceptable for clothing storage.
A cool, dry place is best for storing clothes. If you must keep items in a hot space like an attic, use breathable canvas garment bags or boxes to allow air flow. If a damp area such as a basement is your only choice, airtight containers may be the best choice but take special care to prevent mold and mildew. Adding some desiccant packs such as silica gel can help prevent moisture buildup. Store boxes high up on a shelf away from the floor or walls, which tend to hold moisture. Also consider running a humidifier to keep the dry out the dampness of the air.
If you just have select folded pieces you want to put away, try canvas storage boxes that you can tuck onto existing shelving and move in and out of the attic.
Now that you know the basics of where to store clothes, what’s next?