Costume design sits at the crossroads of storytelling, illustration, history, and hands-on construction. A designer has to interpret a script, render ideas on paper, know how clothing looked across eras, and understand how a garment is actually built. Because those are distinct skills, order helps: start with the design process, add drawing and history, then the technical craft. This path organizes the discipline into a learnable sequence.
Start with what a costume designer actually does, then build the supporting skills.
The design process
Begin with The costume designer's handbook by Rosemary Ingham, the standard guide to reading a script and developing a design, and Costume design by Lynn Pecktal, rich with interviews and real production work that shows the profession in practice.
Drawing and history
Next, build the eye and the reference knowledge. Fashion Illustration for Designers by Kathryn Hagen and The Fashion Designer's Sketchbook by Holly McQuillan teach you to render your ideas clearly. Then ground yourself in period accuracy with Survey of historic costume by Phyllis Tortora, the comprehensive history of dress, alongside Costume history and style by Douglas Russell and The mode in costume by R. Turner Wilcox.
Technical craft
Finally, learn how costumes are built and maintained. The costume technician's handbook, also by Ingham, covers construction and running a costume shop, A practical guide to costume mounting by Lara Flecker addresses handling delicate garments, and Costume Design and Making for Film connects the design work to screen production.
Read in this order, you assemble the full skill set of a working costume designer. Follow the full path, and sketch and sew alongside the reading.