As in most things, there's no single "right" way to tune a ukulele. Experimentation can produce effects ranging from the sublime to the psychedelic. If, however, you plan to learn songs from sheet music and want to play together with other people, it helps to know the conventional tunings of the ukulele.
There are basically two dominant schools of which you should be aware. We refer to them as the Old School and the New School. Practically speaking, there's not much difference between them, but the Old School is a lot cooler. The Old School tuning goes A D F# B (where A is the top string, if you are playing right-handed and south of the Equator, or playing left-handed and north of the Equator, or vice-versa). The New School drops this tuning down a whole step giving you G C E A (where G is the top string).