It's best to put the guqin in a stable environment, with stable temperature and humility. There're two putting methods for a guqin, depending on different circumstances. 

When you often play the guiqn:

You can just put the guqin on the guqin table horizontally. A good guqin with its archy structure and strength can stand the pulling force of the strings. So if you play it continually, you can just keep the strings tuned there and put the guqin on the table without moving it often. There's also an old saying which goes as "a gentleman dosn't move away his guqin without a reason". 

When you don't play the guqin often:

You can hang the guqin on the wall if you don't use it often. Just use a long nail to make it. It's recommended to nail a piece of wooden plate onto the wall before hanging the guqin, this way the guqin can be hanged more vertically, reducing the odds of the guqin being out of shape for long time hanging. You can also put it vertically in a corner of a room or put it into the guqin case, the benefit of which is though this way it can keep possible sunshine or dust. 

Last but not least, please don't put the guqin near fireplace or a room with AC opened.