I love a good plaid button up on any day of the week and no matter how the weather presents itself. My favorite thing to do is layer. If I could I would layer almost anything.
If you want to go with a tomboy look but still be very feminine in character of the ensemble then layer your plaid over a oversized tee or a tee dress and then pair it with a biker jacket or in my case biker vest. Then for the feminine touch (you thought it would have been the dress, HUH?) add your pumps or heels that would rock well with all the pieces you have on.
What I'm wearing:
Forever21 plaid button up
Spiral Girl biker vest
Target tee dress (plain)
Steve Madden heels
Ray Ban shades
Of course, add as much arm swag you can wear.