Placing lights in blender can be a bit difficult at times. One very handy way of simplifying placement, is to make your light the active camera and then switching to camera view. Once in camera view, you can very easily pin-point camera location, but this technique really shines at orientation. Use Axis double clicks to constrain transform to local axis. To put it simpler, if you want to tilt the camera, press R-X-X to rotate around local X axis.
When you are done placing your light, make sure to select your camera, and make it active again else the view will be rendered from the light’s view.
You can also use this technique to adjust the SpotSi (SpotSize), and SpotBl (SpotBlur) values very accurately.
Cntrl-0 (Zero) to make selected object active camera.
Axis double click to constrain to local. (G-X-X; or R-X-X; G-Y-Y)