There are a few things that you can use as general rules, though. Some try to max out their disciplines, but there is a limit to how far you can max them out before the XP expense becomes too expensive. You run into the law of diminishing returns. I typically try to get my two main offensive disciplines to level 3 and my passive to level 2. Beyond that, it's usually not worth the XP
I disagree. If you know the game well enough to know where all the free stat increases are, you can easily get all three of your disciplines to level 5 and still have xp to spend on other things. However, judging by how much xp you've already spent and how much you say you have, I would guess you're either well into Hollywood by now. If that's true, then you've already missed many opportunites for free stat increases and now it's time to play conservatively.
I'm a big fan of stealth, myself. There will be a point near the end of the game where you will be caught in a crossfire between 4 flaming crossbows. They will take you down fast, even with the best defenses in the world. If they can't see you, on the other hand.... Takes about 8 stealth to go undetected for that part of the game, if I remember correctly. That's a lot of xp to spend, but stealth can make every mission so much easier. Of course, as a Ventrue you have the alternative of Mass Suicide (Domination 5) to take these guys out. Still easy, but there's greater risk involved.
Your ranged feat is already 8, which is good enough for anything except the alternate fire modes for the sniper rifles. Since you don't have Auspex, you might consider going for the full 5 points in Perception, Firearms, or both. That's up to you, though. Ranged 8 should be more than sufficient.
You don't really need to have melee or brawling up very high if you're already good at ranged. Brawling will help you feed on mortals you are engaged in combat with, but you're Ventrue. Just Trance the last guy standing and feed to your heart's content. Besides, Blood Buff will raise your strength and stamina both up to 5 if you ever really need to engage in melee combat. Just make sure to kill quickly, as Blood Buff is your most expensive discipline to use. Activating it more than once per fight is not an efficient use of your blood points.
If you were still downtown and had not yet done Larry's "Traffik" mission, you could get your Finance up to 5 without spending any more xp on it. That would help a little with the cost of ammo. Even if you've already done Larry's mission, you can still use the Finance manual downtown for one more point.
Normally for a Ventrue I would strongly recommend taking both Presence and Fortitude up to 5. With both of them running, you are all but indestructible. Only the most powerful enemies would be able to harm you. But if you're as far into the game as I think you are, then don't spend any more xp on disciplines until you're satisfied with everything else.
