1) What would be a typical mistake for someone grilling for the first time -- no, not putting too much lighter fluid on it so the flames whoosh up! A mistake that would mean the coals aren't getting hot as quickly, or the meat isn't cooking as quickly, or the like.
2) What hint would an experienced griller give that would make things much better for the novice? A Secret of Grilling.
ETA: thanks a lot! You've given me a lot of choices, things to consider. :-)