How do I read my Apache logs?
They are stored in ~/.logs/apache in subdirectories corresponding to machine and domain, and are updated every 20 minutes.
Reference: MemberManual/ServingWebsites.
I get a very unhelpful "Internal Server Error" page from Apache when I try to access my dynamic web site content.
Check error.log in your virtual host's log directory. See the last answer for where that is.