Thoroughly review and sign a petition to help save our Second Amendment. Try going here and looking for a petition to read and sign. The pen is mightier than the sword, but you have to actually write the letter, stamp it and mail it. Tens of millions of people feel the way I do about America and the Second Amendment, but they just don't get around to sending the letter. Criminals who are willing or inclined to commit the most violent and heinous crimes known to mankind will not concern themselves with obtaining a firearms permit, will not and have not concerned themselves with which guns they cannot own.
Criminals are criminals because they disobey the law.
The only types of legislation that would work are the kind that the National Rifle Association has been pushing for decades. Project Exile type legislation. Additional penalties should be added to a crime if a firearm is present or used by the perpetrators, specifically punishing those who choose a firearm to commit their crime with. Actually enforcing the more than 23,000 laws already passed by government. Most gun control laws are not prosecuted when broken.