Flexibility Is Not the Issue; Connecting the Moves Is The thing with the grace in rhythmic gymnastics is that it has nothing to do with how flexible you are. It is all about the connection of movements. Even if you do manage to do all the moves right, you might still look stiff. That is because you do not connect them; you just perform them as if you change the photos in a frame. A good exercise to understand what we are talking about here is to lift your arms up for 4 counts, and then lower them back for 4 counts. Do not bend your elbows. This will teach you how to control your arms and not make them look broken in the middle of the move.
Tension Will Make You Stiff Tension. This is something you are not even aware of when you perform. Your body might be relaxed, but your fingers or jaw might be clenched. Even your shoulders might be lifted, and that will give you a stiff appearance. Try to do one of your moves holding something really fragile in your hands, so you have to be careful not to press your fingers. It is a great exercise. Another thing about the tension is that you do not breathe properly while you are concentrated. This will make you hold your breath, and when you do a move that requires more time, you will look stiff because you hold your breath. Try to slowly breathe out while doing the move.
The Connection Between Moves Matters The connection of moves matters as much as the moves themselves. For example, if you make a balance and then step forward, this step should not look like a new move. It should continue the line. Practice any two moves that you connect all the time. For example, take a move with your arm to the side and a step forward and a turn. Try to do these two moves with the same tempo and concentrate on this. Do not rush your second move because you want to catch up. Do these moves slower until you have the same tempo.
Daily Expressiveness Training Even if you do not have a lot of space, you can still practice your expressiveness every day. Start with 5-10 minutes of rotations of all your joints, then try to move your arms slowly to the music, trying to connect the moves with the sounds, but not counting them. Then try to walk across the room with your arms relaxed and your body long. Imagine that you are on a stage. Practice in front of a mirror or record yourself from a distance to see if your moves go outwards or inwards.
Grace is a matter of strength, relaxation, and tempo. Do not try to be elegant; it will happen with time when you start paying attention to how you connect your moves and breathe. With time, you will notice that the moves that seemed so unnatural to you become natural, and even though you are still tensed inside, it will look like you are not.