I got my start on Terry Brook's The Sword of Shannara. Well, it was the first book I bought with my own money after reading a lot of my dads Larry Niven and Harry Harrison stuff.

I would highly recomend it. One of my favorite books of all time. The Sci-Fi stuff might be a little steep for him but any of the Known Space series by Niven or the first books in the Stainless Steel Rat series by Harrison would be good. It's what I cut my teeth on around 14.

__________________
Why did the cat fall off the roof?
Because he lost his mu.

I just destroyed the periodic table. I only recognize the element of surprise.