This is just my opinion, so take it for what it’s worth.
Start with finding out if your state has a state 2nd amendment advocacy group. Check them out. Politicians pay more attention to groups, than to individuals. That group should have some idea of when letters, emails, and phone calls need to be made, and when a group of people need to show up at the capitol.
Also, your state representative should have some time set aside for things like town hall meetings, or to be available at a local office for people to talk to them (might require making an appointment). Occasio-Cortez has apparently been taking some heat for not doing this (people in her district could not get in touch with her), because it’s part of a politician’s job. You can find out what legislation could be making it’s way through the system, read it, then go to their office and talk to them about it. If they won’t make time for you, or their views completely contradict your views, remember that when the next election rolls around.
But dealing with the legislative system is only part of the problem. Public opinion is important, because politicians also listen to poll results. The Million Mom March was quick to see that the internet had potential, and had their local chapters set up websites to help network with members and draw people into their group. They also realized that the other side could use the internet against them, and pressured their members to avoid contact with ‘gun neandertals’, because of how dangerously violent those gun loving, knuckle dragging, inbred, gun lovers are.
Now, there are social media platforms that are easier to join, but the left still holds fast to their “don’t talk to them, they are too dangerous and too stupid to listen to” mantra, because they don’t want their followers to hear information that has not been filtered by them. You are unlikely to change the beliefs of hard core leftists by engaging them on social media, but some segment of their followers is likely to be people who have only heard part of the story and are giving their support based on limited (and probably even false) information. It is those followers who can have their minds changed, when they see both sides of the issue presented. Change enough of those minds, and the politicians will start seeing poll results telling them that supporting gun control is not something that will help get them votes at the next election.