Most of the time, its thinking about situations in my mind. I havent been able to cum much lately but I usually do it first thing in the morning or just before i go to sleep once or twice per week. I think of a scenario and in my mind act it out. It usually involves a guy I fancy or on some occasions, a complete stranger. I do not have to visualise a face or body to cum.
On other occasions, I watch porn, usually gangbangs.
I'm with you LMF, I don't always consciously think about anything. I just think about sensations & feelings more so than a specific person really.
I'm exactly the same, though I - on the rare occasion - fantasise about some faceless Master/Mistress being the one doing everything to me.
It's different when I watch porn and masturbate then, though. It's a mix of the visual stimulation and imagining everything being done to me at the same time, empathising with the sub in the situation usually.
Most of the time its softcore porn pictures and maybe the odd video. When a woman is totally naked, often I dont find it as arousing because most of the time it just looks very raw. Pics like this can get me going easy (hopefully I'm allowed to show you this):
today it was because i woke up in the middle of a very sexy dream so i finshed it off in my mind. it depends on what i've been doing useually reading erotica or thinking about what me and my hubby could do.