Look at the perks and decide. I would say at least perception 4 so you can lock pick all the things.
edit:
P 1: pick pocketing (good if you like that kind of thing)
P 2: Rifleman (great if you are going semi automatic. Works outside of vats)
P 3: Awareness (meh)
P 4: Locksmith (For my play style...max it out)
P 5: Demo Expert (good if you like exploding things and crafting said explosives)
P 6: Night Person (meh)
P 7: Refractor (+50 energy resistance is nice)
P 8: Sniper (Gives you better control when you are sniping outside vats and a possibility for knock downs when sniping with a scoped non automatic weapon)
the rest are VATS intensive and unnecessary for your build. My suggestion is to have at least 4 in perception.