a vivid imagination helps, but so does porn. or hentai, i prefer imaginary people for my handsome time.
touching myself ended up kind of a frustrating project as teenage libido wore off.
what works best for me is laying down on my bed with something (pillow, used clothing) between my legs to rub against.
makes it easier to imagine the pretty invisible thing between my legs is something much bigger.
i know cis guys who have problems getting off by touching themselves, some get better results by humping their bed.