Should I have the camera set to AF tracking or ??
AF tracking is for tracking moving subjects, so will you be shooting moving subjects? If not, you'll generally save battery power with it off.
As to your more general question: you could try one of the low-light/night scene modes. Or if you want to get into more detail, the basic principles are the same as listed in this thread
. (Note: the TZ7 is the same model as the ZS3, just a different name.) Although, I would add that, if you zoom in a lot, you'll want to use a faster shutter speed -- maybe as fast as 1/400 -- to reduce camera shake.
HTH - Mark