First of all, the ability to stop time means that I'd have all the time in the world, so to speak. So, I'd probably start out by using it to catch up on all the sleep I've lost over the years.
Then, I'd catch up on all the other projects that I've been working on, able to do this without interruptions.
Over time, though, I'd probably figure to use my power for good: saving people, righting wrongs, the typical hero spiel.
After a while, I'd end up getting bored with that, and I'd probably let the power go to my head. Starting out by just messing with people's minds, but then turning to a life of crime: heists, mainly.
After that, I'd probably just end up going mad, as I'd be aging at what would seem to be an accelerated rate to any outside observer, eventually just stopping time for good and humoring my insane whims, until, at the moment of my death, I'd release the flow of time from my grasp, letting time flow onward.
Firstly, I would reject my humanity, fight to the death with my step brother. then I'll lose my entire body. and eventually I'll steal his as he dies, and I go underwater for 100 years until some fishermen pick me up, then I gain an ability which allows me to stop time, name it THE WORLD" based off of the 21st Tarot Card, figure out the step brother that died still has descendants, being his great grand daughter, grandson and, great great grandson, figure out they also have abilities like mine, called stands send my workers to go end them, until they all fail, except for one ice guy who kills an egyptian dude and a dog. Then some weird Japanese kid that was once my workers, tries to kill me using emeralds, knowing that no one can just deflect the emerald splash, I deflect them. I use the time stopping ability to time stop and punch a hole and donut him, while yelling SHINEII KAKYOIN" then watch as he dies as he crashes into a water tower. Then he uses emeralds to kill a clock tower, rendering it useless as it no longer works signifying he figured out how my ability works, then some old guy who is apparently my step brothers grandson finds the message out and delivers it to his own grandson, until I yell THE WORLD and throw some knives at him until he dies. Then I fight his grandson and he is mad for some reason. I use my ability to its fullest until I realize he can move in my world of stopped time, then I grow scared and get beat up by his punch ghost stand named Star Platinum, until I tell him that this was my plan all along to drink his grandfathers blood, then I look like some weird gay dude but I am really strong now and I can stop time for 9 seconds now which is pretty good. Then I stop time to go look for a steam roller to crash it onto that Japanese guy named Jotaro Kujo and boom I do it, I won until I realize I can't move and that I realize he can stop time. I say what how is this possible? Then I get my legs cut and monologue about how he's still only human and I squirt blood on his eyes, then I kick him, he counters with a punch and I split into half with blue flames coming from me while my last words are "B-B-BAKANA KONO DIO DAAAA KONO DIO DAAAAAAAA" and then I get disintegrated in the sunlight.