For LEOs, I would advise having an extendable pocket mirror that can be put on your duty belt, or within easy reach in your car. It is worth every cent when you have to stick your grape up into an attic, looking below stairs or even rooms. One thing to remember, if you're using a mirror, you need a cover man (b/c you're not in a good position to defend youself while you're manipulating the mirror). Also, once you "clear" that area with the mirror, you must keep looking at it until you partner visually checks it. Nothing like clearing an area with the mirror, pulling it back, and someone moving right into the area you just "cleared."
It was mentioned earlier that clearing a room by yourself is inviting a bullet. You are certainly at a disadvantage, a very dangerous one at that. But it can be done if you've done it quite a bit. Hoewever, the question that I think you need to ask yourself is, "What am I trying to accomplish and at what risk?" If you're investigating the noises coming from your living room, are the articles in that room worth losing your life over? If your children are in the next room, I think we all know what that answer will be, whether you're alone or not, you're going in. My .02
Life's tough. But it's tougher when you're stupid.