This sticky post will always be a work in progress, so if you are unsure about something, check back here periodically.
Some things that are explicitly prohibited are
Long story short don’t be a jerk!
If you are requiring assistance, please be as detailed as possible when describing your problem. Links to screenshots are greatly appreciated.
Finally, priority support will always trump the general support forums, so please be patient and realize that not all of the questions here may be answered. If you need priority support, buy a developer license.