Couple of house rules, added as and when they come up:
Diablerie.
Diablerie permanently grants an increase of half the difference in generation, if the target is lower, and a point of Discipline (their highest, up to their rank in it)
Siring.
Siring costs a point of permanent willpower.
or
When siring, the disciplines a Vampires starts with are reflected in their sire's disciplines - a vampire with 4 ranks in Potence is unlikely to create a child with 4 ranks in Celerity (each level of natural disciplines inc. 0's represent 1 side of a die, the roll sets starting disciplines). Not including PCs, natually.
Firearms
Ranged attacks use Perception and Firearms, not dexterity.
Modern Crossbows use Firearms. Early Crossbows might not, I'm not sure.