What did you masturbate 'to' before you discovered porn? Imagining being with a girl and enoying the sensations are fine...
Except, if you have an addiction to porn, have PIED etc, it's better not to... Don't just think of yourself being addicted to the hardcore stuff, think of it as an addiction to artificial sexual stimulation - videos, pictures, hardcore, softcore, nice pictures of friends on facebook, erotic stories and literature.
Try and give yourself a break from ALL artificial stimulation for a while in order to 'reboot' your brain. After that, you may be able to have a normal relationship with masturbation, though many of the successful rebooters on here continued abstaining, saving themselves for sex. It may depend on if you are single or not.