Your elbows can be a great reference point as to how your upper body is stacked up.
The first thing to look at is whether they are touching the same points on your torso on each side. For example on your left side your elbow might sit just under your rib cage, and your right side it sits on your hip. Which of course means you are not equally balanced.
To correct this imagine there is a spirit level attached from elbow to elbow and you need to make it balance.
Then ask yourself whether you have equal distance and pressure between your arm and your torso? Maybe one is clamped in with no distance between your arm and your waist and maybe the other looks like a bus could drive under it. Obviously neither of those is ideal so to help them hang more equally and effectively imagine some tiny weights drawing them gently down, then gently close your back arm pit keeping the upper arm still soft; this should engage your lats (back muscles) to assist with maintaining a stable position.
How about your hands? Are they using equal pressure? Are they fixed or do they move too much? Imagine trying to keep the hands still but gently moving the elbows to brush against the fabric of your sleeves so to do this they will move but only very slightly and very gently-this is what you’re aiming for.
I hope these visualisations help you to fix your elbow woes but if you would like some more in depth 121 advice to improve your riding I have some limited spaces for 121 Clients at the studio-WN8 9QP so hit reply if you’re ready to up your game!