The most fundamental way, with direct friends/family, is to use your own likeability to introduce ideas. When people like you and think you know things, they will tend to think your ideas are more correct. If you introduce your ideas in a way that projects security, confidence, and humility (sounds contradictory but it's not), the people around you will tend to slowly absorb them whether they realize it or not.

This may take a very long time and some people you know may never radicalize. They might even go the opposite direction. But there's no perfect path that would convince everyone that currently exists. That wouldn't be a realistic goal. Set a goal of 1 person. Even that might be a tall order depending on your social circle!

Like others have mentioned, working in an organization can be a great way to radicalize people. You basically get to put out your messaging to a large number of people, many of whom already self-selected to be at your cool lefty event or action. A valuable skill is that of the organizer, a person that can recruit and get people to take on projects requiring a group or mass effort. A good organizer plans strategically for what goals they want to meet and how they will accomplish them, then applies personal skills to recruit people, onboard them, and distribute work. The interpersonal skills you will develop when doing this overlap heavily with ways to radicalize people. Direct conversations. What questions to ask. How to avoid alienating most people and how to carefully alienate highly toxic people so that the group doesn't suffer. The act of organizing, of creating live campaigns that keep people returning to your group and gaining their own organizing skills, is the core of radicalization. The people you work with will be the people you help radicalize because they trust you, they like you, and they see you as someone that creates results. Some of the actions you organize can also be 100% about radicalization by their nature. Leaflet some PMC trajectory college students about the bad things done by the sponsor of the job fair. Hold a rally for Palestinian liberation and have conversations with anyone you don't recognize. Screen movies, do book clubs, put up posters, tear down fashy ones, etc etc.

Finally, our task unfortunately includes knowing a lot more about most topics than liberals do. Make sure you do your own readings on history, theory, and media literacy/criticism so that you're ready for the unfair questions. Though again, being liked and trusted is usually more powerful than being right about everything.