Not a doctor, but my go-to for medical advice is:
and the NIH Office of Dietary Supplements for information regarding nutrition/supplements.
I recently looked into buying SSDs in the 100s and the folks at r/NewMaxx helped a lot.
Seconding UpToDate as a starting point and treating it like Wikipedia by using it as a source of references.
Then, you can use those references as a starting point in PubMed.
This suggestion is based mostly on watching my primary care physicians look things up at a major academic (university) medical center and conversations with physicians after using UpToDate + PubMed on my own.
UptoDate for sure. Pubmed for research that is also cross referenced in google scholar.
I've found /r/UKPersonalFinance useful for UK-related personal finance questions.
There's a more general /r/PersonalFinance but I've used it less and I think been less impressed when I have.
The next election: 538; Cook and Sabato; prediction markets.
Live election results: NYT live results; 538 live blog; prediction markets; twitter (e.g., @Redistrict, @NateSilver538, @Nate_Cohn).
(For American politics only. Not comprehensive. I'm not an expert, but I'm an elections junkie and this is what I read.)
For competitive programming questions, codeforces.com. It has a large audience of highly skilled competitive programmers, and someone will normally help you if it's an interesting question.
It seems like one big difference between someone totally unfamiliar with a given field/skill and someone familiar with it is just that the person familiar with it knows a really good (/the best) place (website, forum, potentially even a reference book etc) to look for answers about it.
It seems like simply learning where to look for answers about a given thing gives an instant boost, so I thought I'd ask people to share what the equivalents are for fields/topics that they have inside knowledge of. Doesn't have to be just academic fields, and sources don't have to be websites, it could be "call your local x, they'll have that info right on hand and are actually happy to take calls from the public".
This is obviously in the spirit of the classic The Best Textbooks on Every Subject, but where that aims to answer what you should read when you want to start learning all about a given field in general, here I'm asking where you should go when you have a more specific one-off thing you want answers on.
(I don't remember seeing a post like this before and didn't see one in a quick search, but if someone's aware of one and I'm doubling up let me know!)
In your answer say what topic/field/skill it's about, what 'place to look' you're suggesting, and what your suggestion is based on (e.g. "I've been a GP for 5 years and this is what all the GPs I know use when they have a medical question", or "I'm not an expert but I've personally found this useful").