1 - A small hook to attach to the wall above the tub. This can be a little plastic 'sticky' hook if you have smooth tile walls, or a suction cup hook if you have smooth walls but don't want to use any adhesive on them, or a large cup hook if you have rustic sauna style walls.
2 - Needle and thread
3 - A wire shower curtain 'ring' or similar non-rusting attachment
4- A freshly cleaned tub and walls
5- A shower curtain free of mold and spores. Making or buying a new woven curtain is probably easier than trying to sterilize an old slimy one. Having two curtains makes laundry timing easier.
Frequently asked shower curtain questions
Shower curtains can be washed?? Yes! And they need it... just like your towels need washing regularly.
What kind of shower curtain is best? I recommend woven synthetic shower curtains because the fibers don't hold water, and they wash well. I've used cotton sheets, but totally synthetic or polyester/cotton blends dry faster. Actually, almost any fabric will work to keep water in the tub... anything from canvas (in dry climates) to sheets to to parachute fabric.
Don't I need a coated or solid plastic curtain to keep the water from getting out? No. Think about umbrellas, they are usually one thin layer of woven fabric. Although solid vinyl shower curtains CAN go through the washer, most of us don't do regular loads with hot water washes and hot rinses... and balancing the washer load can be tricky. If you choose to go with the solid vinyl, look at the hem. If it has a sewn bottom hem, cut it off so water isn't trapped inside.
Do I need an inner and an outer curtain? No. The point of having an inner and outer curtain is to keep drafts from wrapping the inner curtain around your legs. If you live in a climate where this is a problem, simply leave the back 18 inches of the curtain open, rather than pulling it shut wall to wall. . Air will move through that opening rather than pushing the curtain against you. Using two curtains also reduces air flow and increases drying time..the opposite of the goal here. If you like the look of an outer curtain, at least leave it open while the inner curtain is on the hook drying.