You can reduce the amount of space required to store things like duvets, bedding and clothes by up to 80% if you use vacuum storage space saver bags, but make sure you get the best from them with this hands on guide. A full written tutorial to go along with this video is available: http://www.neusu.com/help-advice/how-to-use-vacuum-storage-bags-properly/
The video includes best practice tips and advice, as well as showing just how effective the bags are at reducing storage space required. \it uses Neusu's own vacuum storage bags (of course) but is relevant to any make you may have.