By now most people looking for information (but not always) use the search feature either here or google etc.
By now there is also an abundance of (sometimes mis-) information out there and unless someone has arrived from another planet or started using the "internet" last week, reasonable readers can decide with how much salt information should be used.
But to go back to your question, if you have a list of 10 or 100 things you wish you knew when you were starting out that you want to share, you could createa message with just that. Or even submit it as an article.
The other way to pass on the knowledge other than writing a book would be to keep en eye out for questions or discussions that you have something to contribute before the usual suspects chime in