Well, first, study the human anatomy to understand how the female body works. Pay attention to details like the waist, hips, and shoulders. Also, practice different poses to add variety. And don't forget about the clothing and how it drapes over the body.
To draw the female body in manga, begin by sketching a simple skeleton to get the posture right. Then, add flesh and define the muscles gently. Use soft lines for a more feminine touch. And look at references from existing manga or real-life models for inspiration.