I strum with a combination of the thumb and the backs of all the nails of the right hand, that way your hand isn't holding an invisible plectrum and the fingers are ready to be deployed since they're normally sitting around the "home" strings - thumb over 6/5 and ima over 3/2/1
This also allows for some nice damping using the back of the fingers and the heel and even allows you to tap the soundboard quite easily to get a flamenco style rythm going.
It also allows you to avoid resting fingers on the soundboard whilst playing - a very bad habit I picked up and took ages to get rid of.
Hope this helps.