I lie on my side when I masturbate. This is because in my teens we were living in a converted summer cabin and my room didn't have a door, only a curtain. Mom or Dad would look in at unscheduled times so I never knew when I would be completely alone. Obviously I didn't want to be caught masturbating so I quickly concluded that lying on my back with my legs open was not a good idea. I started masturbating when late in Grade 7 and after a few tentitive starts I wound up doing it every night. I still masturbate every night.
I wear a night gown for easy access, always have.
I've heard Mom and Dad having sex, every once in a while Mom would be a bit noisy. They had a quiet non-squeaking bed.
I lift my nightgown above my hips, Turn on my side, lift a leg and cup my labia. I knead and press until I'm very wet and then I slip my middle finger tip in and move it around until it's very wet. I then lift my leg again and rub all around my button until it is all wet and slippery. I then lower my leg and still cupping my labia, this time with my middle finger tip inserted, I rub my button with my thumb. As the orgasm approaches I try to relax as much as it is possible [sometimes impossible to do] because I have discovered that if I can delay the contractions, I can extend the orgasm. For me the beginning of the contractions signals the end of the orgasm. The way I delay the contractions is to relax totally and absolutely with only my thumb moving. During the orgasm I increase the pressure just a bit and slow the rubbing. If I get it right it seems my orgasm lasts forever. Several times I tried to measure the length when I was still in my teens by counting 'one orgasm, two orgasnm, three . . .' Occasionally it all works and I have really wonderful orgasms that last 15 to 20 seconds, but usually they last 5 or 6 seconds or so. Afterwards I still cup my labia, with my finger tip comfortably inserted and I give a big happy sigh and then I have a great sleep.
I only masturbate at bedtime and aside from at the very beginning I have always masturbated this way.
I'm still a virgin, although sexually experienced. I'v been masturbated and kissed to orgasm and I have done blow jobs and hand jobs, the first time when I was 19 and in college. I like hand jobs best because I really enjoy watching the ejaculations, particularly if it just flows out and doesn't spurt. What I don't like about blow jobs is having my head held at time of ejaculation. I don't mind it in my mouth, I just don't like my head being held.
From what I have read, seen in the odd video and from some conversations with girl friends, it seems most women masturbate lying on their back. I wonder how many masturbate on their side as I do.