Since I am renting our home, modification is out of the question. All available conventional storage space is already taken, pretty much up to the ceiling, so no more shelves can be mounted with aesthetic impact that the wife won't tolerate.
As I have said in previous threads, I have too much stuff in my house and need to get rid of some of it.
I think clearing out stuff is the best bet. We have been simplifying and downsizing how much stuff we have and prioritizing what we store. For example we have a two week supply of water (3 gal/person/day) and six months supply of food in our 400 sq ft. apartment. We realized one day when building our BOBs that we needed to prepare to "bug in" as well and prioritize our space to meet our needs. We didn't need 3 pairs of skis and holiday decorations as much as we needed water storage and long-term food storage space.
Good luck!