Always put your cameras in plain view. Don't hide them. Rather than have them hidden and catching the thieves faces, it's better for them to see the cameras and all security before they attempt anything so they move to the next place that is less secure. Think about bouncers - it's better to employ a massive scary bouncer who would scare any trouble makers from doing anything, rather than have a small bouncer that can fight - sure, he's useful once the trouble has begun, but it's better to stop the trouble from happening in the first place.
The above is to deter the amateurs (99.9%)
If you have something specific that the professional thieves have come for, they will get it regardless of what security you have in place.
I have full day and night vision cameras in plain view as well as sensor flood lights all around the building. Big bright yellow bollards in the driveway. Clearly visible bars on all the glass areas. If they look through the front glass door, they see themselves on the security monitor.
Perimeter sensors at every accessible point of the building. If they do break in, I have rotating laser sensors (like you see in the movies) sweeping all the areas inside the building. When the alarm goes off, I have smoke screens being realeased so they can't breathe unless they lay on the floor, strobe lights go off and high db piercing internal sirens. So they'll be rolling on the ground unable to breathe, hear or see.
Until not long ago, if someone was in the building, the thief would also be met by the barrels of several guns. Sadly I don't have the guns anymore...
You make something idiotproof, they'll make a better idiot.