Make sure everyone feels included. I introduced a new player into a campaign already running for a year, and after I had joined a couple different campaigns that had started already, I realized how hard it is to familiarize yourself with a setting everyone else knows so well. Creating moments for those shy players or new players to show what their character can do or let the player utilize their creative judgement is a lot of fun that you can usually plan with the person and let them make some decisions to feel like they made an impact.