Okay, here we go again. Time to lose the guilt and abandon sentiment.
Take a big shopping bag and go around the house filling it up with stuff you don't actually like or have moved on from liking.
Never mind that it was a gift. It's the thought that counts, so keep that.
Note: handmade stuff that the giver gave you within the last couple years and which you know they'd be horrified if they found you'd given it away or sold it should probably be given back to the maker. It's a tough call, but if the "it just doesn't fit me/my home" conversation is going to be less painful for them than the discovery that you tossed the giant portrait of your face they laboriously made out of your favorite flavors of jelly beans, then fess up that you value them and their kindness and their friendship, but just don't have a place for the gift anymore.
Take the plunge and purge the stuff that makes you sigh with resignation when you look at it. Just think how nice it will be to never have to see it again!