wow...that is a bit of a problem....there's over a a thousand x-men comic that have been produced....and there's the different titles, but i would recommend these three:
X-men
Uncanny
Astonishing (newest)
but i think it'll take you years for you to read every comic to get the low down on the characters...so my advise is that you go to a marvel encyclopeida and get a brief bio on the main characters
PM pr1983 and/or Sage Tessa ...they are the most informed x-men readers i know
Sage Tessa
Why, thank you, ayjay...
A good place to star is: UXN, UncannyXmen.Net...
It's jam-packed with information about most of the X-Universe... swank