Hermione is intelligent, practical, and at some times, bossy. I love how much she cares and how hard she always works. This Coolest Hermione Granger Costume is a fairly easy costume to put together because chances are, you already have the parts!
I first wore a white collared blouse (my mom had one) under a black buttoned sweater. You can find the blouse in the school uniform section of a store (because, hey, it is a school uniform you are trying to make!). Depending how cold it is, you can also wear a black sweater-vest instead of a full sweater. The full sweater is more legit, however, to the actual character.(I recommend any regular clothing store would have these items, or you could always make them yourself!)
I printed the Gryffindor logo from the computer (just experiment with sizes to find what looks best on you) and mounted it behind red construction paper, just to make it stiffer and easier to tape (or pin) on my sweater. Or, you don't have to wear the Gryffindor logo because it is actually on their school robes, not their sweaters. I just wore it to make the costume more recognizable.
Now the important tie. I was fortunate enough to find a red and gold tie from my dad, but if you don't already have one.... See if you have a plain red tie. You can sew/pin/or even tape gold ribbon (or fabric) in stripes on the tie.
I wore a black pleaded skirt. You can wear gray, but just make sure if you do, your sweater is also gray. I found the skirt in the school uniform section of a regular clothing store. I wore knee-high black socks (again, gray if your other pieces are gray) and black ballet flats.
One of Hermione's signature traits is her big, bushy, mane of hair from staying up late and studying. My hair is already pretty thick and bushy (partly from staying up late studying, too), but to make yours even bigger, you can brush it with your head down. It will add volume and static electricity. I've also heard that teasing your hair will work, but it would take a lot longer. If that fails, I'm afraid you'll need a wig to get the legit "Hermione mane." If it will be difficult to keep big and bushy, try spraying it lightly with hairspray. It should be pretty messy; don't spend forever to make it look nice.
I didn't carry a wand because this was for a marching band parade. I'd recommend for a wand, though, to find a smooth stick or piece of wood in that shape. I found a wooden dowel that would have worked perfectly.
This is a very easy costume to make and it will sure to get a lot of compliments, even from people who aren't Harry Potter nerds!