I like a combination: TruGlow TFO nightsights (good in any lighting conditions) and Crimson Trace Lasergrips. Use the sights for initial target acquisition, only use the laser for last second precision targeting. Make sure the part of the home most likely to be where Badguy's going to have to come through, living room, dining room, Great Hall of whatever, is illuminated all the time - a seven watt flourescent bulb's good for that. You want to be able to identify your target without becoming a target. So if you shine a flashlight or laser at Badguy, he's likely to shoot you before you can do anything. Same thing with chambering a round in the gun - don't make noise, don't shine lights. Identify your target clearly from behind cover or concealment if there is no cover.