if you stay at a disney resort, you can sign up the night before for the mears shuttle that does the drops offs for day visitors to universal.
seats are limited so sign up at the concierge desk in the resort lobby.
even the value resorts have the concierge help desk.
last i knew it ran $14 pp rt.
you will get a pick up time when you book the shuttle.
other choices are town car, taxi, rental car for the day.
you can get a rental car at the disney car service.
if you rent a car, add in the parking charge for universal parking.
the city bus will take you 1 and a half hours to get there.
you take the bus to sw at dtd. then take the other bus to the drop off at the universal stop. walk to universal from there.
it cost about $2 one way pp.
i wouldn't do the city bus.......too long......