Nothing says "fall" like the reappearance of masculine touches in the wardrobe. Take this lovely ensemble seen on The Sartorialist. Men's watch and masculine shoes with neutral shorts and oversized sweater. Depending on what continent you're on, the scarf may be a feminine or gender neutral touch.
Adding masculine touches to your wardrobe can be simple. Try a feminine cut in a "menswear" fabric (i.e. often scratchy or pinstriped!). Also note that since men's clothing tends to be baggier, a chunky sweater vest (think grandpa-style), a baggy cashmere sweater, or most "boyfriend" cuts are a little more masculine. You can also save the look for just accessories, with a chunky wristwatch like seen above, a man's ring (especially in leather), or even a tie a la Annie Hall.
To avoid going too tomboy, pair these items with feminine pieces. Skirts, sexy heels, and tops in delicate fabrics like chiffon and silk look especially alluring. And the classic rule still applies: if you go big on top, go skinny on the bottom, and fitted on top means looser on the bottom. Those boyfriend jeans? Those would look great with a body-concious hammered silk tee in a jewel tone and high heels. Your oversized sweater? Pair with skinny pants or leggings and flats, and throw in some over-the-top costume jewelry for good measure.
How are you incorporating menswear trends into your wardrobe for fall? Or are you ignoring the whole thing and catching the trend when it comes around next year?