After about Day 100 I start building in more dangerous areas for more difficulty. I start in a town, then a city, next the hub city at 0, 0 on consoles, then I build in the wasteland (more dogs, it's harder to gather resources because of dogs and landmines), then I try using only certain weapons.
Like right now I try to only use the Blunderbuss (one of the loudest and slowest guns in game it brings more zombies) and maybe a sledgehammer. Plus you can always lower the block durability so you dig faster as well as zombies digging faster, and raise the difficulty of the game.