After looking at several scripts you'll start to notice two types of 'set' commands - SET and SETA. So what's the difference and which one do you use when?
The SETA command is used to permanently assign binds, commands & values. The values set using the SETA command are storeg in your etconfig.cfg. These are 'permanent' settings since they're stored in the game's default config files.
The SET command is used to assign TEMPORARY binds, commands & values. The SET command can be used to create temporary CVARs that are available as long as you're playing ET. As soon as you exit the game, these temporary values are lost.
SET vs SETA
So which one to use and when? The SETA command is used for permanently storing all the game settings. The SET command is good for storing all your binds and cvar values. For example, a weapon toggle script would use the SET command since the value of our weapon toggle isn't permanent and keeps changing (hence the toggle effect). Another example, your FOV (field of view). When RtCW starts you would use a SETA command to set ur base FOV settings. If you made a script that toggled your FOV you would use the SET command to create the temporary values of the toggle. That way, when you finish the game and shut down the next time you start back up the game would default to your SETA fov value rather than whatever temporary FOV toggle setting you were on when you shut down the game.
As a rule of thumb, only use the SET command for cvars you create and use the SETA command for permanently storing the values of your game settings. It's also a good idea to use the SET command instead of SETA when changing your settings by typing them into the console itself.