Read the sheet music before you play to find any trills in the music. Count the notes in each trill to give yourself a guide on how to play them.
Find the beat and the time signature of the music on your sheet music. Set your metronome for the beat of the music and the time signature.
Tap your foot to the beat of the metronome as you play to keep your playing in time to the music. Play quarter notes in time with each foot tap, two eighth notes per foot tap and four sixteenth notes for each foot tap.
Hit the first note of the trill on the down beat, which is when your foot hits the ground. Play the first and second notes with two fingers, one for each note. Take note of any alterations in note speed, such as adding an eighth note or even speeding up into thirty-second notes.
Continue playing as normal after the trill is finished. Repeat the process each time you come to a trill. Practice regularly until you can play the trills easily.