Count the cha-cha rhythm to all the music that you listen to. Cha-cha is in 4/4 time, which means that there are 4 beats to a measure. You should count it as 1, 2, 3 cha-cha, 1, 2, 3 cha-cha.
Practice your steps while counting out loud. You can either do this alone or with your partner, though it's easiest to do it by yourself. Focus on making your movements match the rhythm as you count rather than matching your rhythm to the movements.
Use very small steps to begin with. At this point, your goal is to master the cha-cha rhythm, not the dance.
Listen for songs to count the cha-cha rhythm to all the time in order to keep the sensual and energetic cha-cha side of yourself flowing with creativity. There are probably a lot of songs that you listen to every day that could be perfect cha-cha songs if you listen for the rhythm.