Have him gain the reigns of leadership in Santa Prisca, preferably governmental status where he could wage wars and remain untouched, though leading some kind of mass rebel organisation in his home country, or branching out into a serious terrorist group might be interesting
He should be Batmans equal both mentally and physically, so no being beat down on by the Bat or even Az-Bat, and none of that crap where he went off an worked for Ra's only to look incompetent. He shouldnt have been lusting after Batmans woman either, that just made him look stupid because you knew he'd always be in Bruces shadow when it comes to Talia
None of that cheap 'gun for hire' routine he seemed to turn into, that totally ruined his character for me, he just became another thug who got clobbered by Batman. The stalking and tiring out of Batman was what made his character for me, the way he toyed with Bruce then just swooped in for the kill and took over Gotham. That was his main strength and he definately should have stuck with it
Keep the venom too, turn it into not so much of an addiction, but a trump card he plays when he cant win with his ordinary strength. I was thinking about the Venom develeping some sort of insanity inside him, but then he'd just become another one of Batmans crazy villains, he should be so much more, up there with the DCU big dogs