It is easy to create this or that image in the imagination of readers. But if you want them to see a person with a specific appearance, hopes and dreams, then you need to do exercises daily to work out the skill of creating a character.
Try to list the five most important aspects of your own story: your family history, where you were born, important events, etc. Create a character that looks different from you, but has the same key events in your biography, see what kind of personality can be formed as a result.
Now create a second character with an opposite life story using the same five-aspect method. How can these two characters interact with each other if life brings them together?
Create three or five characters that differ from each other in at least four points (height, weight, facial features, desires, obligations, gender, intelligence, dress style). At the same time, at one point, they must all coincide.
Try to create a 1-2 page comic sketch containing couples talking. Use dialogue, facial expressions, body language. For example, draw a scene in a bar where a female undercover agent is looking for a murderer and a guy tries to hit her.
Take two expressions from the list and put them on one face: confident, indecisive, frustrated, frustrated, flirty, mischievous, tired. Then give the list to your friend along with your drawing and ask them to guess where which facial expression is reflected.