How to decipher the MS?

[ReneZ]

Here are some necessary, but certainly insufficient, steps involved in solving the MS.

1) Be aware of all assumptions you are making, also any unconsicious ones. The last part is, by its very nature, not easy. 
Example: if you assume it is a cipher, you must be aware that you probably won't find the solution if it is not not a cipher. If you assume there is a plaintext in Latin, you may not find the solution if there is an Arabic plain text.
It is not forbidden to make any assumptions at all. One just has to be aware what are the consequences of them.

2) Be aware of the various statistical analyses that have been made in the past, and what they already tell us. 

3) Make sure you have another hobby that brings occasional moments of achievement. ;-)

That's really it. The advice from my web site, that was quoted in the opening post, does not lead to any specific steps to be taken, but always keep it in mind when working on it.