I've handled books of the condition you describe, many times, and seen them handled and stored many more times than that - so, I assume we are discussing what to do in lieu of conserving/restoring.
Purists insist using gloves, and I would agree IF there was to be a lot of handling of the book.
There is a risk in using gloves - the risk of doing damage by unintentional catching/tearing of old paper on the cloth.
I wouldn't touch it with gloves on at all unless I'd been changing the oil in my Harley or making Christmas butter cookies or changing the baby, and would touch it as little as possible in general.
To preserve (excellent word) I would interleave each and every page with neutral pH tissue cut to the size of the page if doing so would not unduly stress the end binding.
If interleaving between every page would endanger the end binding, then I would try interleaving every other page.
There are two types of such tissue. One looks sort of like greenish wax paper, and the other looks sort of like wrapping paper tissue. Either one would work fine, the thinner the better. The papers come in many sizes, which can be trimmed.
The objective would be to stabilize the pages, and then to get the book in a Solander or Hollinger box built to fit it closely, and then to store it out of the light away from any moisture or heat or critters. It may be displayed, hopefully behind UV-filtered plexi or glass glazing.
Baggie storage is okay, as a temporary measure, but not long term. It needs to breathe a little.
As to the relative humidity necessary to keep it from deteriorating further, the chances may be good that your own home is about right as it is - unless you like the ambient atmosphere VERY dry or VERY moist, or if should you like the temperature and/or humidity to change frequently - all of which are not good for artifact storage.
Extremes of temperature and moisture, and frequent changes between the two, are the primary enemies of paper artifacts. Most delicate things can survive very nicely IF those 2 matters are well managed, even if not ideally.
Here is a good link for obtaining good archival storage supplies of all kinds:
http://www.usmilitariaforum.com/forums/ind...showtopic=26375