A light source guide for attachment to a bottom of a grip of a handgun, a bottom of a firearm magazine, a hand tool or the like, used for resting on top of a portion of the light. The guide is adaptable for receipt on different sizes, shapes, types and lengths of light sources. The light source guide preferably includes a guide base having a upper surface and a first rail and a second rail extending downwardly and outwardly from opposite sides of a bottom surface of the guide base. The first and second rails and the bottom surface of the guide base are preferably adapted for rapid engagement to the top of a suitable light source. Also, the guide base can include at least one aiming wedge disposed between the upper surface of the guide base and the bottom of the implement to which it attaches. The aiming wedges are used for adjusting vertically the alignment of the flashlight beam relative to the line of sight of the handgun or hand tool so that they at a selected distance.