Here's my favorite way to masturbate! I usually do so at night, when left alone, after looking at porn or solo stories to get turned on during the afternoon or evening.
I particularly like to fantasize about giving physical exams to girls that involves them being topless. I then create excuses that they need to take off so and so clothing one by one until they are nude, then I make up something so I touch them, until I orgasm. I usually use some girls I know at school which really turn me on, but occasionally I use a celebrity figure. I sometimes carry this on, holding my orgasm, so I can do it to several girls.
I masturbate by taking my fingers and rubbing with the tips of my fingers, like I was spinning something, the top of my penis, slowly at first, then a little quicker, this creates great orgasms. Sometimes I finish myself off by humping the bed, adding a twist to my fantasy :)