For avoidance of doubt, this answer is not an official statement of Stack Exchange policy; it is simply my understanding of how the site works.
So long as you are attempting to actually answer the question and remain with the guidelines outlined in the Code of Conduct, very little is required in an answer.
About the only exception to the above is if you have a relationship of some kind or another with a product or service you mention, you should mention it in your answer - this is covered in the "How not to be a spammer" section of the Help Center.
It is always helpful to indicate your level of expertise when it comes to an answer so that readers can make an accurate assessment of whether they need to get further information before proceeding. For most subjects we cover here on Photography SE, it doesn't matter that much if the answer is wrong; however, if an answer covering legal matters is wrong, it could result in significant financial losses and/or prison time - so therefore an increased level of warning about any legal answers is perhaps wise. However, it is not required: no answer anywhere on Stack Exchange should ever be constituted as providing legal advice. Law SE unsurprisingly takes this slightly further with a disclaimer on every page:
Law Stack Exchange is for educational purposes only and is not a substitute for individualized advice from a qualified legal practitioner. Communications on Law Stack Exchange are not privileged communications and do not create an attorney-client relationship.
The same thing should be taken to apply to every answer in the network.
Stepping back slightly, a large amount of the use of IANAL/TINLA etc is because it is an Internet trope.