West Coast's roots are in Lindy Hop, the style of dress is varied and diverse. However, there are several constants.
Shoes: The best and most common type of shoe for men is the standard heel ballroom shoe. I personally use Freed of London's Professional Modern Flex shoes, because they're sturdy, long-lasting, and can point and flex easily. I dance on average 50 hours or more a week, including teaching and social dancing, so the sturdiness is really a factor. But these are not for everyone, and even I have to use inserts in my Freed's so I don't kill my feet. For men who want to dance long hours and still be comfortable the entire time, the best option is the Ultimate Depth Balmoral shoe. The Lycra option feels like you're wearing socks, but is still snug and firm, and there is almost an inch of padding in these shoes! If you're a more advanced West Coast Swing dancer, consider upgrading to a taller heel. Both Freed and Ultimate offer taller heels (1.5" to 2" should do it) and the extra height is good for keeping yourself forward-weighted, legs straight, and to have good point... among many other benefits.
Shirt: West Coast has lately taken a few cues from the Country Dance scene: Embroidered and studded/sparkly men's shirts are prolific. If that's your style, awesome, there are plenty of places you can get shirts like that. Affliction and Roar are two brands that spring to mind, and you can find them rather cheaply on Ebay. But if that's not your style, stick with a well-made dress shirt, 100% cotton. Your choice of brand is subjective, and I've had great success with brands ranging from Express to Perry Ellis to Murano to Prada. As long as it fits and looks good on you, you're good to go.
Vest/Jacket: One thing that Lindy Hop gave West Coast Swing is a lot of vests. Your standard 5-button waistcoat is very common and looks smart and stylish on most body types. It allows freedom of movement while still keeping your range of movement free. Suit jackets and blazers see some use as well, though they are not so common because of the risk of getting a girl's hair stuck in the buttons. However, if you can pull it off, have at it. A good looking jacket will dress up even a jeans/t-shirt outfit and make you look more professional.
Pants: You have a wide range of options for pants, gentlemen. Some basic rules though: They should fit, they should breathe, and they should stretch. Yes, stretch. You'll be doing a lot of moves that require some stretch in your pants as you get better at WCS, and no one wants to rip their pants in the middle of dancing. For jeans, I use Lucky Brand Denim... most of their jeans have 3-5% spandex in them and they fit me well. Shop around to find your preferred jean style as everyone is shaped differently. If you prefer to use dress pants, half-lined 100% wool pants will do just fine as long as they fit you correctly.
Shoes: I've seen students and friends try lots of different brands of shoes, but really the Comfort and Ultimate brand shoes marketed by Dance Connection are the best value for money that I've seen. They're comfortable, padded, and reasonably priced. They're also designed by a Podiatrist who was tired of his feet always hurting when he danced. Get the Block heel in 1.8" or 2.2" height. Color and sparkle level is completely up to your own personal preference :)
Shirt: The best shirt for WCS is entirely based on your body type. Accentuate your best features, but follow these couple of rules: Keep your left underarm free of obstruction, and give yourself freedom to move. That means no corsets or restrictive tops, and no sleeve flaps that block the left underarm, as the leader's hand will get caught on it. West Coast dancers tend to favor flowy and sparkly tops that move when the arms are raised, but by no means should this be your only option. If you have a great, flat tummy feel free to wear midriff baring tops. If you have an hourglass figure, a backless or skintight top might be your speed. If you're really skinny, a tank top and small cover-up will give you some added presence, as will a well-fitting flowy shirt. Experiment with what looks good on you, twirl around a few times to see how it moves, and express your own personality with your fashion choices.
Pants: That's right, pants. West Coast really emphasizes clean, straight lines, and a skirt breaks up those lines early, oftentimes ruining them. A good pair of boot-cut jeans or dress-pants will do nicely and help emphasize the straight legs and good lines that West Coast dancers strive to make. If you want to draw attention to your bottom half, go for white or brightly colored pants. Otherwise, blue and black work.
Hair: I say this a lot, but I'll say it again: Never ever wear your hair in a ponytail! Unless you really really enjoy whipping your partner in the eyes with that weapon on the back of your head, keep your hair down. You can still pull it back away from your face if you'd like, but having your hair all the way down is commonplace for West Coast dancers.... many will even style their hair specifically so that it looks good while dancing! A great example of this is Jessica Cox, who I've almost never seen with her hair up.
Pro tip for women: Spray some perfume into your hair. It will often be in the leader's face, and that extra bit of pleasant scent will make you all the more favored for another dance.
The most important thing is to have FUN. Your most important accessory is your smile. Dance with everyone, be friendly, and even if you're wearing a Rainbow Brite costume you'll still be everyone's favorite.
Pulled from http://www.adamasanborn.com/west-coast-swing.html