Trainzack

Okay, first, two things about my tutorials:

1. I will not provide the very basic information, like "how do I compile a map?"
2. I will generally cover the stuff that's obscure, and things that I haven't seen tutorials of before.

Now, what I am about to say next may be considered basic information, but everyone needs to know it: Never, ever, EVER use the carve tool. Also, the hollow tool should be used sparingly.Now, some other information that can be helpful:

1. Sounds are played from an ambient_generic.
2. Logic_auto and logic_relay can work wonders.
3. Displacements should never be made into a brush entity (ctrl + T)
4. A good habit is to make all of your brushes with the nodraw texture and use the texture application tool to add textures to only the necessary brushes.
5. If you're making a func_tracktrain, then it has to be facing east (right in the top down view) or it will be in a weird direction.
6. Design your levels with optimization in mind, especially if you're making a large multiplayer map. Make sure there are very few or no places where you can see to the other side of the map, as this can cause lag.
7. If you are making a map for the portal series, it is always a good idea to make the puzzles require figuring out the solution rather than split-second overcomplicated moves. [ED 2021: This is subjective, not objective]
8. env_explosion and env_spark are good entities for effect.

And that's all for now.