Surface lights are just a "Hack" (not to put a dampner on the awesome stuff ericw achieves) as far as I understand it. What happens is that you set up a light entity with a key that has the name of a texture in it, and at compile time that entity is duplicated repeatedly over all surfaces with that texture. It's the sort of thing you could do yourself, if you had the patience of a robot. It's pretty effective though with the caveat that if you wanted some of those textures to be lit and others not to be you'd have to have two of the same texture with different names in your map.

Feel free to correct me if I'm wrong about how it works, it's been a while. 

In case I didn't make it clear, the light that's emitted depends on the values given to that original entity, so there's nothing picked out from a texture or anything like that. (For picking colours from a texture, I like to use shareX's screen colour picker, it can give you the numbers in a format that you can just paste into an entity.) 

Why are you posting without a name? 

Yes, it just duplicates one light entity over faces with specified texture name. Saves time when you have to edit lots of duplicated lights. 

I thoroughly approve of this situation. 

for light from lava in explorejam 2 map 

you set up a light entity with a key that has the name of a texture in it, and at compile time that entity is duplicated repeatedly over all surfaces with that texture.
Wow, good to know, this is gonna save me heaps of time! One thing though: would it still allow lightstyles on specific lights, like a neon blinking while others don't? 

I tried surface lighting on lava but found it to be very erratic, I think because of how the surfaces are chopped up. Some lava looked fine, while in other places didn't seem to emit any light at all.

What it's really best at is light emitting textures that have an obvious source in the center. You save having to place many lights, and they are all consistent throughout the map for color, brightness, etc. 

I'm pretty sure light styles work, switching the light on and off definitely does. Targetnames are retained by every duplicated light.

If you want some of them to do one thing and others to do another, then you'll either have to do ugly things with your brushes/textures or handle the lights manually. As far as I know there's no way to edit the individual lights that get created, they're only added when you compile.
(Maybe if you decompile your own map... but seriously?) 

"−surflight_dump" command line option for light.exe saves all of the generated lights to a file "mapname-surflights.map", so you can then paste the copies into your map and edit them individually. 

http://imgur.com/a/p6jZt
From this screenshot you can see how i light my maps, hundreds or thousands of low emission lights that i tweek after i have vised my map, i move them change the values, and its difficult. How do the Pro's create lighting in maps? 

compile often. take your time and compare diff setups.
in the end you will get a feel for it. 

I am not a pro but try this out:

Place a point light near a light source texture with:

light: 400
wait: 3

After that, test your map and you should notice that the light sources appear to be the source of light.

Now add some fill lighting around dark sections of your map (Darkness and shadows are important so don't go crazy!)

Light: 100 - 200
Delay: 5

*Keep in mind these are just numbers, you'd have to adjust and play around to get to where you want to be*

That should give you a good start. There are many different advanced techniques and better ways to do things depending on the situation but try that out! Like MFX said, you'll just get a feel for it after testing things. 

ok! :) 

Enlightning Techniques for the masses.
I found this Sock mail i think it is helpful for you:

* Never place symmetrical light sources in a room
* Never use global ambient light, learn to light maps properly
* Place strong light source first before placing additive fill lights
* If a room lacks strong shadows, tone down fill lights
* Consider shadow area contrast when placing source lights
* Understand the advanced features of wait/delay
* Try to keep light/wait values consistent for light source types
* Always sync light entities to actual light sources
* Always Illuminate the primary path
* Light Flicker (style 1) can be useful for focus in a room
* Play with up lights for ceiling detail focus
* Lights can use mangle/angle parameters for directional spotlights
* Lights should always create interesting shadows
* Place strong lights for large shadows, fill lights to soften the edges
* Switchable lights are perfect for creating dynamic detail
* Place identical light sources at the top and bottom of platforms so that when the platform is in both positions it looks right for the light source

Got it? Good. 

Great tips, guys, thanks! And Eric, thanks for the workaround. 

Understand the advanced features of wait/delay
These are a bit cryptic. Is there a tut somewhere? 

 

For the less experienced designers. 

I gather they have something to do with how far the light reaches and its intensity at the source, but I need to learn how they work. 

https://shoresofnis.wordpress.com/guides/lighting-basics/ 

...hehee 

Makes more sense now. Bookmarked. 

This is sometimes useful to refer to:

http://quaketastic.com/files/LightTest.jpg 

Yes, I already had this pic, but it's not as clear regarding which param does what as Skacky's link. Plus, it doesn't showcase all scenarios. It's still a good immediate reference, though.