I think bars suck, and are a fire hazard as well. Automatic metal roll shutters are the shit, however it's important to randomize your activities so that any thieves that have staked your place out (neighbors) never know when someone is home to meet them with a shotgun or not. I'm thankful I don't live in an absolute shithole, though it's rapidly turning into one and I'll have to consider such things. Some natural plants are also great deterrents and avoid local bylaw infractions like maximum fence height, no razor wire allowed, etc. There are great bushes with thorns like steel nails, basically impenetrable even with a chainsaw. I don't think too many thieves will bring heavy equipment.