In thinking about what is on this thread, it seems to me that many people are calling for laws that are already exist in many places, if not everywhere. Ownership and transfer of fully automatic weapons is heavily regulated. Modifying a weapon to fire fully automatic is illegal. Selling guns across state lines is illegal. Background checks and safe storage laws are becoming more common.
I will suggest that what many of you need to do is either petition your state legislatures to pass laws like background checks that your state may not have, or severely beat your politicians to enforce the laws they have (Illinois/Chicago I'm looking at you). I know, somebody's going to say it needs to be done at the federal level, and they won't do it. Well, that's what we have state governments for.
This would be, as you say, a start.