I made an album for my Mom's 80th bday a number of years ago. Except for some very early pictures, I didn't necessarily do the book chronologically. Instead, I did a page of:
pics of her and her grandkids
pics of grandpa and kids
pics of grandma and grandpa together
pics of weddings (hers, mine, my sister and brothers, etc.)
one page for each sibling
one page for each grandkid
pics of my Dad and the uncles in uniform (they all served in WWII)
pics of the sibs all together
pics of cousins
you get the idea ...
It made it a little easier to organize and then I didn't have to worry so much if I got the order of events wrong. I also did some journaling in advance, but did the rest with my Mom after I gave her the album.
Let us know if you need more tips. I know it can be overwhelming, but it's an awesome gift!!!