Remove any references to customers from your answerbank
Often you'll naturally reference a company name in the answer to a question. E.g. "The project for Acme PLC shall be completed on time and on budget". Whilst this will make sense for the document the answer was intended for, it will always need to be rewritten in future documents - and worse than this, it leaves the risk of inserting one company name into another's proposal!
It's usually worth removing the customer's name from the question too - as this will be used in matching. The questions in the Answer Library should read as concisely as possible. This will help matching and also make it easier for people to read in the future.
Everyone is responsible for Knowledge Base health
The best time to keep the library in good health is always now. If you or any member of the team spot something that can be improved, then they should do it there and then. As soon as it's updated, other documents can benefit, and it's much more efficient to spend the time as you think of things or have reached a good understanding of the problem space - that why we prompt users to update the library at the completion of every question.
Use variants sparingly
Try not to leave too many variants in questions however, as it will just make the job of someone selecting one in the future harder. You should avoid similarly worded variants in general.
Always take your time when completing questions to update the library
When a question is moved to Complete - the user should have a complete understanding of it and it's context, and feel like the answer given is the best possible (at the time). Consequently, this is the perfect time to update the library. Care should be taken at this point to do so, as leaving such jobs till later will risk them not being done, or forgetting important context, so take the time in the moment. You'll thank yourself later!
Carefully select which documents to seed the library with
Not all past documents need to be uploaded to the library. It's usually best to start with the most recents and work backwards. When you feel like you're not adding anything anymore - that each document you upload already has matches to the majority of questions, it's time to stop, and you have a well populated library. The number of questions/answers a library should have is very dependant upon the industry and task - and could be anywhere from fifty to a hundred up to thousands.