Well, I didn't want to contribute to the already conflicting theories (although I am glad someone started a what-it-is-NOT list and somehow happy that it is longer than the what-I-did list(s)) but I thought to throw in what I did and didn't do, with remarks on 'why' (as in how I 'prepared' based on reading old and new theories on how to get this sidebar). Ahem:
(I did NOT get the sidebar).
1. I did think (naively) that the recent Editorial was a clue. I thought 'snow' and I thought 'icy' although NOW that I know the sidebar is (not)* entitled Happy Holidays, I reflect more upon what I did.
*EDIT: Thanks Daze, it is called Winter Holiday? Good to know.
2. I did just so happen to have received/sold/sent a Happy Holidays card.
3. I have no Christmas/Snow pets/petpets (I simply abhor the cold, wet/icy season called Winter as well as the holiday Christmas, sorry.)
4. I did have an ICY Eye SNOWball equipped to my main active pet. I sent the same type snowball to a couple of Neofriends. I had the same item in my Inventory as well.
5. I visit Snowager every day I am awake and he isn't.
(2/3x per day)
6. I try Taelia quests several times a day and do them when I can afford.
7. I received/scratched/sold Race to Riches Scratchcards in Happy Valley and regularly visit/refresh/buy from the Igloo Garage Sale on Terror Mtn.
8. I did miss a day of Advent due to power outage, but that seems to be NOT a requirement as many have mentioned. I also did watch every one all the way through before collecting, but that also seems NOT a requirement as many have mentioned. (I used a direct bookmark link to Advent but I often navigate through Happy Valley to get a Scratchcard.)
9. I am sure I received a few REs, even one Winter one, IIRC, but to be honest I don't get many more than that. A few a month if 'lucky' it seems.
10. I am using the Taelia Snow Faerie avatar, although the avi one uses also seems NOT to be a requirement.
11. I admit I did not check to see if my pets Mood (Happy?) or Health. I never enter them into the Neolodge ('cause I admit I am a cheapstake lol) and my firstborn/active Nimmo seems miserable/unhappy almost all the time despite what I do, so I have come to largely ignore her mood. All my pets are always well-fed regardless of mood, Satisfied to Bloated.
12. I did not check my NP on hand, not thinking that mattered. I do tend to think it is mostly 'random' or there is more than one requirement plus a little luck? I did experience the Altador plot bug for a couple of days, but other than that had no problems on the site (even Godori always worked).
13. It appears from the data, that those who got the sidebar are still overlooking something, but it is hardly a user's responsibility to keep tabs on every single "stat" at any given moment. I happen to think that it could not have been something that one did all this MONTH. After reading the posts of people that had and had not gotten the sidebar during the first HOUR of the 31st, I really do think it is something very" minimal".
(And I will edit this post if I think of more to add to my list.)
EDIT: I did not donate or pick up anything from the Money Tree, IIRC.