I'd recommend the first appearance of the character from AMS 129, just to see where he came from and how it all started.
Then I'd suggest anything Punisher appeared in during Frank Miller's Daredevil run of the 80s, as I feel that interpretation effectively redefined the character and set the table for his first miniseries (where he fought Jigsaw).
After that, I'd say his first two running series, The Punisher and Punisher: War Journal. The early issues of both series are pretty good.
After that, I don't know because they stopped doing really great things with him for a while and I got bored with the entire concept.
For the Daredevil TV show, I think his inclusion will be pretty well handled.