The costs of treatment, meds, and surgeries need to lowered and it will be good. I believe that a person should keep more of what they earn to spend on what they want like healthcare or more toys. People who can't legitimately work due to health reasons get the works in terms of healthcare, living expenses, rent and food in welware. If a person is partially disabled and can only do certain kinds of work then the government should train them and have them work for the government.
My overall goal would be to reduce murders with guns (murder in general) by removing gangs, improving the education of poor people and stomping out crime in poor areas. That would likely reduce the lion's share of it and have a long term positive effect on the people living in those areas.
For school shootings, put metal detectors and armed security (ex-military) into each school. That would drastically lower the frequency and severity of those shootings.
With general mass shootings, making it easier for authorities to arrest, seize weapons, block the sales of guns to a person, commit a person against their will if they make threats or start displaying certain warning signs. Also making the authorities responsible (more so) for not doing their job in preventing or not stopping it like in this recent school shootings. Ya can make all the laws you want but they won't do any good if they're not enforced. These ideas would do alot more in preventing and stopping these things then trying to ban assault rifles or all guns.