I guess I'm a HL woman, although I wouldn't describe myself as ravenous any more- I'd love to have sex 5-7 days a week but 3-4 is just fine as well.
What turns me on? Lots of things. I suspect I'm more visually stimulated than other women- I love looking at nude men (and women) in the flesh. (Pictures are nice, but not arousing unless there's some actual fucking going on). I'm primarily attracted to my s/o, but I do occasionally have a flare-up of lust for others, maybe once or twice a year. I also have many other turn ons- D/s play going in both directions, sensual kissing and fondling, dirty talk, spankings, feminisation (even the soft variety) of bi/straight men I'm intimate with, roleplay, wish fulfilment, so on and so forth. I'm a bi switch. You name it and I'm probably down. (No poop, blood, animals or kids basically).
What makes me want sex is I think a mixture of hormones and cognitive reasons. I was masturbating at a young age (11/12) and absolutely couldn't wait to have sex. I've always been, um, very sex-oriented. So obviously there's some innate, subconscious drive there. On the other hand I get less spontaneously horny than I did when I was younger, but my desire for sex hasn't wavered that much; often my desire for sex begins consciously, thinking about how nice it would be to make love to my partner when he is home with me, and I plan our evenings out accordingly. Like, 7PM supper and chat, 730-9 we watch TV or game, 9-930 we go for a walk, 930-10 we chill on our respective PCs or read, at 10 or 1030 I ask him to cuddle with me, and from there I make my move. In bed by midnight. Every other day or so, this is how I work to make time for intimacy. When I get the spontaneous horniness going on, I usually just tell him how horny I am for him and see how he responds. Our deal is even if he's not into sex, if I come to him really needing him, he will at least go down on me, but often by the time I'm 'done' he's aroused enough that we have a quickie. :p
Hope that helped somewhat. HL people and LL people seem to be on two very opposite ends of the spectrum, but maybe my bit about planning sex in such a way might be helpful to you guys. I know for my semi-LL partner, knowing what is going to happen helps take the pressure off of him to initiate.