Great question Maria Elena ! Long answer- lots of trial and error and working with a teacher that can take you through some "body testing" to help determine your unique ROM and proportions. Shorter better answer (albeit sometimes unsatisfying) is that the work is to navigate to the presence inside the posture rather than looking to achieve a certain shape/depth/outcome in our asana. Teachers and self-study time and patience and a whole lotta tenderness:)
This is absolutely, amazingly fascinating!! I have always been so hard on myself for not being able to look the same as so-and-so in such-and-such pose. And while I realize that some of that will come with time and growth, how refreshing it is to switch from a negative thought pattern, to the positive thought pattern of appreciating my unique skeletal structure!!