The best course of action, of course, is trying to prevent efflorescence before it manifests itself all over your walls. As you cannot control the chemical additives in the building materials, the most effective method of prevention is by closing up the pathways and sealing out the water that would otherwise bring those salts to the surface. To do this, it is recommended that you treat your concrete walls with a concrete sealer (the specific type of sealer will vary depending on the material of your walls, check out Ghostshield's line of concrete sealers). A good concrete sealer will serve to penetrate the concrete, both keeping out water while simultaneously sealing up the aforementioned pathways to the surface.
However, if you've purchased a new home only to realize that efflorescence is already an issue, use the Hydro-Etch 1000, specially designed to clear up efflorescence and etch concrete, washing away the built-up salts to leave your walls unmarked. Even if you successfully clean away the efflorescence, it is important to deal with the underlying issue; if you do not seal up your wall with an effective concrete sealer, the salts will simply build up again in the future, necessitating further cleaning and eventually threatening to deteriorate your concrete, leaving your home susceptible to mold, mildew, and other such issues.