The Cha Cha - as I am sure you know - is a fun and flirty dance that has energy and personality throughout. As one of the dances that is usually taught first, it holds a lot of the techniques necessary for many of the other Latin dances as well.
It is necessary throughout this dance to keep your toes connected to the floor and allow all your steps to work through your feet. There are NO heel steps! (I often say that you should imagine a £50 note under your toes - and if you lift your feet off the ground ... you lose it!)
Another important characteristic is the hip movement. What most people don't realise is that the hip movement that you can see when watching performers or competitors stems from a completely natural movement that occurs when you have one heel on the floor and one not. Of course, it can he heightened and exaggerated and at times pushed beyond what would be needed on a social floor, but a relaxed easy hip movement is completely achievable.
If you stand with your feet together and simply bend one knee and remove that heel from the floor, you should find that your weight moves slightly over your supporting leg to help you balance. The easiest way to do THAT is to sit into your hip. If you then just switch your weight onto the other side and change bent knees/lifted heels, you will have already started a natural hip movement.
What I am trying to say is that your hip movement comes every time that you put your heel down during the dance - which for Cha Cha, is all the time! Just think about letting your hip push slightly out every time you put your heel down on each foot and you will quickly find a natural amount of hip movement will infuse your dancing.