In your own space, rec at least three fanworks that you think would make a good intro into XYZ fandom. Rec a fandom overview, a introductory picspam, stories that define and shape the fandom.
If at all possible, try to pick a smaller or rarer fandom, one that maybe doesn't have the following you feel it should.
I'm going to rec some key Mythbusters works. There are only 66 works on the AO3, so I think it counts as a smaller fandom! There's also a DW community, myth_confirmed
I already reccd one of Toft's Mythbusters works for my Day Two post - The Pinocchio Fallacy - in that one, the trope is robot!fic (Jamie's a cyborg). Toft is one of my favourite Mythbusters writers and I recommend reading all of her works in the fandom - they're all excellent.
Another one by Toft is In Search Of - it's apocafic, and kidfic, and it's heartwrenching and lovely.
Then there's Robots Need Love Too by Toft, which isn't robot!fic in fact, but an AU set on a space station, about Jamie and Adam as neuroatypical kids.
It's mandatory to rec a genderswap fic, so here's A Supposedly Fun Thing Adam Will Never Do Again by sabinelagrande - also a great read.
And finally, I'm going to self-rec. Merry Christmas, Galileo is an epistolatory genfic about Adam and Jamie as friends, which I wrote a couple of Christmases ago, so it's still fairly seasonal.
Oh, and I covered Mythbusters art last year for fanart_recs - Here are Adam and Jamie, and the rest of the recs are all here.
It's a fun little fandom, and definitely in need of more love.