I thought this video had some good insight and tips.

https://www.youtube.com/watch?v=JrZfbudbBW8

Very good. A problem with riflescopes is they are often stored objective up in the gun cupboard. While lens caps would seem the obvious answer, makers often warn that air circulation is needed to prevent fungus.

So, I either use the cap but not engaged at the ocular end or, put a loose cup of plastic food wrap over the objective.

In the field, try to cover the upper lens surface to prevent rain getting on it but, if it does, resist the urge to clean it unnecessarily. As long as the centre of the lens is not obscured, a few drops will probably not prevent your taking a shot.