First, you need to know how to identify which string is on which fret. For example, the top string on a G string is on the second fret, and the C string is on the third fret. Similarly, the 'o' on top of the G string indicates that the string is open. You'll also need to know which finger is fretting the string. You can always use your middle finger, index finger, or other fingers to fret the strings properly.
Another important tip when learning how to read ukulele chords is to remember that the diagrams are not always easy to understand. Even if you've read a song score many times, it may not have included a chord diagram. A basic chord diagram consists of a simple circle, with a number next to it, which indicates the fret number. If there's no 'fr' symbol, the chord is played on frets one to four.
Another great way to learn how to play ukulele chords is by playing the song backwards. John Lennon wrote "Because" to sound like Beethoven's "Moonlight Sonata" backwards. Other notable performers who used this technique include Paul Weller, Benny Goodman, and Bjorn. Ukulele acts include big bands, solo artists, and indie stars.