Inside the house you can try to find space behind, under, and even inside the furniture (beds, chairs, sofas, tables). You can buy or make special storage furniture yourself or alter the existing one. You can hang some gear on the part of a wall, at the ceiling, and drape it with a curtain of sorts. I've heard of people sawing through the drywall and making hidden stashes in the walls behind paintings and curtains. Or you could build a new decorative storage wall somewhere in the house. The same way you can rise the floor at some spots/rooms (like a square podium under the bed). Same for the parts of the ceiling (e.g. shelf above the door in a small corridor). If you have 2 story rooms - use the under the stairs space. Or, perhaps you just need a tall and deep cabinet?