​1. Length Adjustment.
Shortening or Lengthening: One of the most common alterations, this involves adjusting the curtain's length. Curtains can be shortened if they are too long or lengthened by adding extra fabric or reattaching the original fabric if possible. The length should ideally reach the floor or hang just above the windowsill, depending on the style.

2. Width Adjustments.
Narrowing or Widening: Sometimes curtains may need to be adjusted in width to ensure they cover the window properly or to fit a specific space. This can be achieved by taking in the fabric on the sides (narrowing) or adding fabric to the edges (widening) to provide a fuller look.

3. Adding or Changing Headers.
Different Pleats or Styles: The header is the top part of the curtain that attaches to the curtain rod. Altering this can change the overall appearance of the curtain. For example, changing from a simple rod pocket to pinch pleats, grommets, or eyelets can give the curtain a more sophisticated look or make it easier to hang.
4. Reinforcing or Changing the Hem:

Fixing or Modifying the Hemline: A curtain's hemline can be altered for both functional and aesthetic reasons. Shortening or adding weights to the hem ensures the curtain hangs properly.