Be picky about what (and who for that matter) you bring in to your home! You are, after all going to live with it for a while.
Before you buy something, make sure you really want to keep it around for a good amount of time.
I recommend going shopping on your own or with a professional decorator to avoid buying pieces on a whim simply because your best friend or mother thinks it suits you.
By doing this you'll have less junk lying around and won't have to spend time sorting and managing it (se yesterdays post) when you want to get rid of it.
Only have things in your home that you truly love!