From the summer through the winter, a blouse that ties at the neck is a perfectly 70's trend that will look office appropriate no matter the weather. Wear one with shorts and flat sandals to add polish this summer, and layer under a vest with trousers or a skirt and boots come fall.
The Classic 70's style: tie that hangs straight down below the collarbone.
You can take a number of tie-neck blouses and wear them this way by unbuttoning the top down to the lowest button you feel comfortable leaving undone, and tying the tie low just above that button before arranging it to hang straight down.
The girly style: tie that hangs in a bow around the base of the neck.
This is the more commonly seen iteration of the style, which looks more sophisticated than a cascade of ruffles. This style can be a bit on the stuffy side, so pick a cool print to keep it looking fresh. Also avoid the office stereotype by pairing it with jeans rather than a pencil skirt, and you'll look professional and stylish, too.
The sophisticated style: tailored button-down with a tie at the neck.
A crisp button-down with the addition of a matching neck tie is an interesting twist on a simple button-down, and different enough from the above styles to serve some androgyny to your office (or everyday!) look.
The bold style: oversized tie that's more embellishment than functional.
This style is more formal than others, but can be dressed down with denim and flats easily. The bow should be starchy to not look painfully girly, and should be the most dramatic part of your look so it doesn't go over-the-top. Kristen Wiig's makes a statement on the red carpet, and the black and white is both bold and posh looking.
The schoolgirl style: white button-down with a black necktie.
Then again, you can always model yourself after Serena Van der Woodsen and try the ultimate schoolgirl style, a white button-down with a black necktie that looks like a variation on a basic men's tie. To keep the look from going too far, pair it with denim or leather and add simple but edgy accessories.