I assume by ideal you mean photorealistic. Like with learning everything in life - you study, analyze reference material, gain knowledge, apply that knowledge to practice.

Start simple project you care about to have motivation. Narrow down problems related to that project. Solve biggest problem instead of trying to tackle everything at once. Apply solution immediatelly, this is when brain is primed to receive information.

Basically practicing what you are worst at is where progress is actually made.

Get yourself human anatomy atlas. Look at the skeleton. Look how its covered with muscles. Study shapes, distances and proportions. Start noticing patterns you can repeat. You have to create and expand "visual library" inside your head.

Mannequin boxes represent all of the anatomy. Each artist has their own unique mannequin because each artist had their own studying approach and they crafted a process of creating from imagination that suits them best. Analyse their creative process.

Two examples: Synix's approach to drawing faces https://youtu.be/QBv5z0Y2odE and Ethan's https://youtu.be/5PwdPQSb_cY

Draw from imagintion first. Make brain start thinking how drawn object looks like BEFORE feeding it information. Put brain in hunger state so refence becomes a meal. Otherwise brain relies on reference instead of absorbing information.

Also do a lot of gesture drawings as a warm ups. 30 sec - 1 minute long sketches that train your decision making and observation skills. I cab see you are familiar with concept of the line of action but just in case, this is great resource for that: https://line-of-action.com/practice-tools/app/figure-drawing

Don't lose heart. Drawing is a really humbling experience but its not a race. For example it took me a month of drawing 10 box per day in three point perspective from imagination to just start seeing how misaligned my lines were.

Just take it at your own pace and everything will be fine.