Thank you for all the responses and suggestions on my rambling "how can I be more welcoming to new community members" post - I wasn't expecting it to get much attention, but quite a lot of people have commented. I do intend to reply to everyone, but it is 2am and I keep falling asleep.
Currently I've got a few ideas. One of which is to revamp my pinned post at the top of this blog and make it more fit for purpose, including encouraging people to get in touch if they would like some support in getting involved in the Tumblr FFXIV community, as well as outlining some of the things I might boost or post about. I could also include some useful links and stuff like that.
I will continue to reblog posts from smaller and newer FFXIV blogs (as well as posts I just happen to like) on @sparkleblogging - and I will also try to interact with them more by leaving comments and/or sending them Ask Lists or other things in which they might want to participate.
And I will come up with a more detailed version of the "Rumour has it...." post, with options for people to request something more tailored to their tastes, which I can then direct newer members towards as a way into engagement and talking about their OCs.
Obviously some things are easier to achieve than others, especially with a full-time job and an executive function disorder getting in the way, but those are some of my ideas for things I can work towards.
Watch this space.