The hook with the Tremere is almost always knowledge. You offer to tell them whats going on and most of them will jump at the chance. Occult stuff usually works too. Be sum you know what youre doing before you offer them any magic books or anything like that - those have a habit of coming back to haunt deal-makers who didnt know what they were dealing with. Sure, you get rid of that pesky Mage, but look what your chief rival has up his sleeve now.

Which leads to the next Tremere hook. They like to think that they are the smartest vampires in the Camarilla, and you know what? They probably are. In fact, ifs almost a given that the majority of the Tremere are going to be significantly smarter than you. Your job in manipulating them is obviously not going to be out - thinking them, because you cant. Feign ignorance, and let them explain things to you, thinking that they have a willing dupe. Its also almost a given that theyll let drop more than they wanted to. Then you figure something out that they havent, and youve got them.