Obviously, most of these will eventually be featured in the frequent questions, which collects questions that get linked a lot. However, until they get listed there, this collection might help provide help finding the best "duplicate master". Also, some of this could use better canonical answers, I'll be putting up some bounties, where the need is ...
The nearest we have to this (that I can easily find) is
How can I buy Bitcoin via a Credit Card or Paypal?
The Q is horribly dated, it talks enthusiastically about MtGox and seeks answers for MtGox.
There are 28 answers. I have no idea whether the services mentioned in various answers are still useful or have gone out of business.
This question ...
Doing a quick search, there are a lot of questions from users that are likely victims of this sort of scam. However, given the fact that this scam preys on uninformed users, pretty much all of the question posts frame the actual problem poorly. In many cases, you have to sort of read-between-the-lines to realize OP is a scam victim.
So I think a good ...
Why is my transaction not getting confirmed and what can I do about it?
Probably has the most canonically worded question title, although this is another good option.
I think a good answer could reference either/both of the below question as well:
Do unconfirmed transactions expire?
How do miners select which transactions to include in a block?