invest in a shotgun, or a couple of mastiff's
while your on vacation have a relative or friend stay in your house a couple of nights, and get those things that turn your lights on and off, some of them can be set to differant times every night of the week.
motion sensing lights are also a good idea, expecially when you get them not only in the places where people would need light, but also in the places where no one should be, so if they are trying to bypass the known owns, another one pops on.
big dogs and guns are definatly the scariest. on less of course your dealing with crackheads.