Well, I would suggest reading Deadpool’s current comics. Deadpool, Deadpool: Merc With a Mouth and Deadpool: Team Up (I haven’t read this run at all, but I hear it’s hit or miss). STAY AWAY FROM DEADPOOL CORPS. The art is shit and the story is confusing. I also really liked X-Men Origins: Deadpool. The art was top notch and the story had a great juxtaposition between funny Wade and dark Wade.
I’m sure Veronica would suggest reading Deadpool’s original run. It has much more character development and shows Wade’s darker side instead of the wisecracking killing machine that’s being shoved down our throat right now. Cable and Deadpool is also a title Vee and myself would suggest.
Hope this helped and sorry for answering your question so late!