Not a whole lot you can do. Especially with low frequencies you're talking about.
Stopping sound requires one thing: MASS.
You'd have to greatly increase the mass of your doors, windows, flooring, you name it. The other thing is sound works like water. It finds its way through the smallest holes. The whole thing is going to have to be sealed to have any real effect.
Do a google search for people trying to soundproof rooms in their house. You'll start to get the idea. Usually it takes multiple layers of hard fiberglass insulation, sheetrock, etc with rubber isolation mounts between the different layers.
Its not as easy as just getting new windows or something. And its the opposite of cheap.