The hospitality of your parish will improve tremendously if you simply gather a small group of committed community members and ask them to say “Hi” to those young adults who come to Mass every week. Remembering names and past conversations can make a meaningful impression on young adults! Consider gathering a group of young adults and going to Mass together, even if it is just once a month. Make time for a discussion of the weekly readings and homily after the Mass.
Meanwhile, relevant, sincere preaching will attract and sustain young adults. Offer your pastor feedback about his homilies, especially noting how you think young adults will receive his style and content.