It cannot be too strongly stressed that it is essential to buy the right fabric for the job in hand; otherwise you will be wasting not only money for the material itself but also for the trimmings, linings and actual making-up.
The choice of curtain fabric is immense but not all fabrics function in the same way or have the same life span and durability. Some materials launder better than other: some require dry-cleaning only. Some are resistant to sunlight: some fade and even rot when constantly exposed to the atmosphere.
Fabric is made up from natural or man-made (synthetic) fibres, or from blends and each with varying grades of durability. It is important to read the manufacturers label when buying fabric particularly the cleaning instructions.
Some natural fibres shrink if not pre-washed; cotton is a good example of this. Some synthetic fibres fray badly if not stitched or hemmed correctly i.e. viscose.
If you are unsure about possible shrinkage, wash your fabric before sewing. Remember to wash with it the trimmings etc. When hemming your curtains allow for a generous hem, loosely stitched so it can be easily altered if any shrinkage has occurred. However, if in doubt it may be a wise idea to go along to a dry cleaner.
When purchasing your fabric buy a small sample first and then match this against the rest of your décor. Check all fabric lengths for flaws, spoils and ensure that the pattern runs square.