Anyone have good material on more advanced rendering effects, related specifically to 3D FPS weapon firing?

For example, one concrete thing I want to implement is a flamethrower akin to what you'd see in Tremulous

And then just in general other shooting effects like flashbang/projectile, lasers, ...

I saw a decent page once I think on the official Valve wiki I can't find now... Related to how halflife/source handled these kind of things.

I think the primary fundamental basis is a particle system based on billboards?

I would love to find that exact valve page again if anyone has that link, and of course any other good pages.