I start massaging my labia majora with two or three fingers to get myself warmed up. Then, I put a small bit of pressure on clit before dipping my fingers into my now wet pussy. After coating my fingers in my own lubricant, I go back and circle my clit. In five circles or so, I slip my fingers down to penetrate my vagina. This pattern goes on for a while until my legs tense up and I near orgasm. As orgasm nears, I increase the pace of the circling. When I'm cumming, I like to press my fingers against my clit and just hold them there. My clit tends to get so sensitive after an orgasm that the rate at which I had been stroking would be too much for my post-orgasm clit to handle.
Other times, I will put one finger on either side of my clit and just rub and squeeze myself to orgasm. I used to tap my clit through my panties, but that was only when I was younger because now my clit isn't as sensitive.
Duration really depends on the day, the stimuli, and the purpose of the masturbation. Many times, I will just masturbate so I can fall asleep in which case, the strokes are slow and I am in no hurry. Other times, I just have an urge and want to get off quickly.