Yeah, I mean obviously add stuff that sounds good for the track, but always consider placement and room in the mix.

Panning.

Well again, no fixed rule, I`m into the Mid/Side methods (that have long time been tightly kept secretes in production circles) to place things within the stereo field rather than using left and right panning, with techno anyway, due to the nature of club soundsystems.

But yeah, pan wherever, extreme panning may well sound duff on a club rig though, so I wouldn't advise it.