Going to Brooklyn NY First time should I rent a car or take taxi?

I wanna be able to see all the touristy things and just wondering if it would be cheaper and more effective to rent a car rather then take a taxi or subway. I've never been on a subway or in taxi also so I don't know, I just dont want to get lost or jipped by a taxi. What do u think?? I'd be brining my GPS unit with me also.