A newbie autograph ball question

[almostdone]

I am new to collecting autographs. I am drawn to, as a lot of collectors are, to signatures on baseballs but I have a few questions I was hoping for some clarity.

I have noticed some browning on slightly older balls in varying degrees. What is it from and how would I protect my collection from getting them or from getting worse?

Also, how much does it affect the value. I'm sure it have to do with the individual collecting as well as the severity and placement of the spotting but does it affect it greatly like centering or worn corners on cards or just a bit?

Thanks in advance for any insight. Any other help would be appreciated in tis new collecting area as well.

Thanks,
Drew