A wrinkled shower curtain isn't among life's great tragedies, but it is an annoyance when you want a nice smooth look. There are a few easy fixes that will have your curtain hanging smooth and wrinkle-free with very little effort on your part.
Obviously, if your fabric curtain can be pressed, that is the quickest way to get it looking neat and smooth. Be careful, since some fabric curtains may be rubberized or have a vinyl backing sewn into them. Check the care instructions for the curtain before trying to iron it.
If it's not imperative that you smooth your fabric shower curtain quickly, you can try misting it with water from a spray bottle, tugging gently on the hem to pull the creases out and letting it air-dry. Doing so will smooth minor wrinkles. Sometimes you will want to repeat the misting more than once.
For a fabric curtain, sometimes warm moisture works better. The simplest way is to run very hot water so that the room is warm and steamy. Close the room for a while to let the steam penetrate the fabric. Follow up by letting the room air and dry thoroughly to prevent mildew.
If you have a clothing steamer, run it over the fabric. This solution is obviously more labor-intensive than just letting the room fill with steam, but it's more environmentally conscientious. It also delivers a hotter and more intense jet of steam. Again, make sure to let the room air out afterward.
Once again, if you're not in a hurry, the packaging folds will often hang from your vinyl curtains with the passage of time. It can take several weeks, so be patient.
To the decreasing process of vinyl shower curtains, it may be necessary to weight the bottom to "pull" the folds out. The trickiest part of this solution is finding someplace to hang them where the bottom is several inches from the floor. Try hanging it over the top of a door with a blanket padding the top of the door to avoid making more folds.
Get several slacks hangers with the clamshell fasteners and attach the clamshell part to the hem of your curtain in several places, below where the horizontal folds are most severe. Hang small, heavy objects from the hook. The crease should be instantly removed. Leave the weights in place for as long as you can. The idea is to train the vinyl to be smooth.