In Camp McCarran where the monorail directly to the strip is located, you can gain entry to the monorail. Take the long way around and stay as close to the vending machines as possible. Follow the wall around the back way. Make sure the other soldier cannot see you. Crouch and sneak up to this soldier from behind. You may hear the phrase indicating that if you get any closer they will have to shoot you. However, as long as you remain hidden, it may flash "Detected" briefly for a few times. As soon as you are close enough to the door, you can go through it and take a monorail directly to the strip. Be careful when returning to the monorail from the strip; you will probably be shot. However as soon as you enter the monorail it resets, and you can again ride it back to the strip. By using this trick you can bypass many quests, and can skip directly to meeting Mr. House and finding the person who shot you.