The elegant art of ballet has a mechanical side to every position and movement. Understanding anatomy and which muscles create the movement you want, helps you enormously in knowing how to improve at ballet. You can learn to define your weaknesses in an impersonal way. Sometimes your weakness in ballet technique comes from just not knowing how your muscles work.
If you are a young ballet student or an adult beginner, organize yourself by learning the correct way to execute ballet movements, one at a time.
Or start before you make a move - you can improve all your ballet by learning correct posture. Good posture in ballet is the same as general good posture. There is no extra tension in the upper body as all the elongating support is in the lower abs and pelvic area. This doesn't mean that the upper torso muscles are not pitching in as the lower muscles change position and tension level - but the upper back/shoulder/neck muscles don't "hold" your posture at all.
Your core muscles - lower ab and pelvic/low back/hip muscles hold your posture. Then you add turnout.
So if your next exploration is turnout, it is best to find a good illustration of the low back/pelvic/hip area showing the muscles and joints clearly. (A picture is worth a thousand words....).
Learn how to stretch the rotator muscles, the piriformis and the adductors (inner thigh) muscles.
With correct posture and turnout you have a basis to develop beautiful basic ballet positions. If you can define your most basic weaknesses in classical technique, and search for every detail as to the solution that you need, you will learn how to improve at ballet with an excellent understanding.
Here is more info about where to get ballet turnout exercises.