One of the Boys.

Clemence Poesy is my favourite example on
 how to pull off the boyish look.

So, I've been talking about it a lot, but I've never given a full insight on the boyish look I love so much. I think the reason I love it so much, is simply because it holds two of the things I love most, and brings them together in a style that only few people can show off. It's subjective to your posture, I guess. You cannot slouch when working the boyish look or you'll look frumpy and simply like a girl who wants to be a guy, not a girl who knows herself. I know a lot of people who are under the impression that girls who want to work the boyish look, are simply 'coming out' when it's complete crap. Think of Audrey Hepburn, or my beloved Clemence Poesy (pictured.) They both achieve(d) this look and still look(ed) absolutely fantastic, and feminine.

• Don't wear bright colours. Think browns, blues, blacks, grays and olive green
• With pants, it's either high-waisted, or it's skinny leg jeans.
• For more of that feminine touch, go with high-waisted, wide legged pants.
• Think about Trilby's. Wear Trilby's. Love Trilby's
• An essential for this look is the classic blazer, whether it actually belonged to your father, it doesn't really matter, but don't buy one that is shaped. It's best if it sits straight down. 
• The boyish look is there to achieve masculinity, so showing off your beautiful curves with through the outfit off completely with a fitted blazer/jacket.
• That's not to say that you can't have an hour glass underneath it.
• If you're really more on the feminine side, think of trousers in a beige-peach kind of colour.
• Simple shirts and t-shirts, in a white, or a blue. It can have a slogan, or a small image, but nothing too over the top.
• If you do go with a Trilby, have your hair down.
• DO NOT WEAR A BOWLER HAT IF YOU ARE GOING TO THE BOYISH LOOK. I'm sorry, but bowler hats are simply too feminine. I love them, do not get me wrong, but I wear bowler hats with  dresses, or when I'm not going to be boyish. I just think it's daft wearing a bowler hat when trying to work the boyish look!
• For shoes, go with a pair of work boots, brogues, winkle-pickers or (to be feminine) a pair of mary-jane heels in a colour like brown or black.

Edit: 

• Keep it calm with simple black tailored shorts, but shorts NEED to be high-waisted if you're wearing them with this look. I can't explain why, but just no. The only things that should start at the hips when working the boyish look are your skinny leg jeans.
• For bags, carry around a cross-body messenger bag or satchel. It's simple, but effective.