Something that I believe helps is to tint your windows just dark enough to obscure viewing inside (not so much that it's dangerous to drive though!). Here in Florida, you can actually get a waiver for tinting windows. Just tell your eye doctor that your eyes are extremely sensitive to light and have him/her sign the paperwork. Costs 8 bucks for the life of the vehicle, and you can tint them as dark as you want....legally! Most people don't know that one here, and illegally tint their windows anyway. I'd rather have a "get out of jail free" card if needed for only 8 bucks.
I run mine at about 20% (which is basically just matching the rear tint on the front windows). Once I put a sunshade in the windshield, you really can't see anything inside the car. I don't think most "snatch and grab" thieves are going to bother with a car if they can't see their obvious easy target. They also wouldn't be able to see you "hiding" things, as the tint obscures their view of you before you exit the vehicle. Just food for thought, and certainly won't deter the determined thief if they think you have something they want.
I run mine at about 20% (which is basically just matching the rear tint on the front windows). Once I put a sunshade in the windshield, you really can't see anything inside the car. I don't think most "snatch and grab" thieves are going to bother with a car if they can't see their obvious easy target. They also wouldn't be able to see you "hiding" things, as the tint obscures their view of you before you exit the vehicle. Just food for thought, and certainly won't deter the determined thief if they think you have something they want.