A quite good way of doing proper lights needs a few more entities. Here's a small setup i use:
1. prop_static : You choose a proper model to fit you map. For a lightbulb you find some fitting models in
interiors.
2. light : Put a normal light entity directly in the lightbulb model. I
usually use a light and light_spot entity so my light isn't very
bright. You could choose for example a brightness like "255 251
204 20"
3. light_spot : The light spot entity is a lot better than a simple
light as you can change a lot more properties. Here are some properties
of my example:
Brightness: "255 251 204 50"
Linear: "20"
Quadratic: "30"
Inner Angle: "30"
Outer Angle: "60"
Focus: "1"
Pitch: "-90"
4. point_spotlight : To give the light that cool beam.
Pitch Yaw Roll : "90 0 0"
Spotlight Length: "60"
Spotlight Width: "60"
Color: "255 251 204"
Flags: No Dynamic Light
5. env_sprite : Last but not least a little sprite entity to give the bulb the last glowing touch.
Render Mode: "World Space Glow"
FX Amount: "150"
Sprite Name: "materials/sprites/glow06.vmt" (or one of the other glows, they are all quite nice)
Of course you can tweak each of these settings to fit your map, these
properties just serve as an example. If you use the sprite and
point_spotlight you won't really see if the lightbulb model is on or
off, as they make it look very bright.
This is the result of my example: