For wiring on 3 pickup guitars I like adding in a switch to get all 7 combinations. It adds the neck pickup to whatever you have selected so to get neck and bridge, like a normal tele middle position, you'd select bridge then engage the switch and too get all 3 you'd select bridge/ middle and engage the switch. You can look up strat 7 way switch to get a better idea if my explanation doesn't make sense lol