Looking for a reference book

[ready2knit]

Hi all,

So like many people, my shape is my own and doesn't always conform to designers' measurements. I was wondering if there was a book that would clearly and easily explain how to modify patterns to create a custom fit. I know you can't change a pattern too much, but I often find that sleeves are much bigger than my arms and I could sometime use a bit of room around the tummy. ( I think I've just described myself as an Umpa-lumpa!)
Any suggestions would be greatly appreciated.