One suggestion to increase participation on Lemmy of those already here is to encourage people to spend some time just looking at the "all new posts" feed. I look at it a few times per day and was surprised at the number of Lemmy groups that I never knew existed. There are far to many groups here that started out good and just faded away. If it's an interest of yours post there and try to rejuvenate the group. Message the existing moderator if you can be added as a mod for that group.