The easiest method of tuning your ukulele is to use an electronic tuner. How to Tune Your Ukulele With an Electronic Tuner
Learn one that will aid you in everyday playing and become your go-to method for ukulele tuning, but also study the others so you have options and alternatives in case your tuner breaks. Each has its pros and cons and can be used in different situations.
There are several different ways you can tune your ukulele. The interval distances between the strings are: a perfect 4th (G to C), a major 3rd (C to E), and a perfect 4th (E to A).