In terms of aim, it is difficult. I shoot an awful lot, so really I am just concerned with not hitting her in the eyes.I can only really aim for lower or upper face and if aiming high I tell her to close her eyes.I will alternate between high and low to try and give a complete coverage. I find it impossible not to get at least some in her hair. Probably my favourite facial was with Suki, the Hungarian redhead in Bristol a few years back, I absolutely splattered her.
The only problem with being a heavy cummer though is that some girls are not that keen to have a second facial from you and some clean up their faces quicker than otherwise, so you sometimes miss out on the wandering around with cum on her face phenomenon.The other problem is that much as I enjoy facials, I far more often come inside a girl doggy style (covered) or cim. It takes discipline to pull out for the facial and like others have said, I don't want to be wanking for a long time, I have to be very close to cumming. And going back to what the op said, it is not something I have done with civvies, I would just be worried what reaction I would get if I ever suggested it.