Aside from the usual combination of jeans/shorts & hoodies, here are a few other styles that you can use to go with hoodies:

Lounge-Around Casual
Since heavy cotton hoodies can only be casual, save these for off-duty days. If the hoodie is baggy, style it with fitted skinny jeans or ultra short-shorts to control the volume. Go for simple, casual tops underneath like a fitted T-shirt or halter top. This look is perfect for a movie or board game night with friends at home or just a quick dash to the library.
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Streetstyle Cool

Adding a few catchy accessories and a statement piece can update your hoodie instantly. Avoid the one that's most worn out when creating this look. Style it over a button-front plaid shirt, roll up the cuffs and then team it with check shorts over bright-colored tights. Finish with a pair of sneakers to create a classroom-perfect look that's bound to keep the boredom away. Other options to try include pairing with a mini skirt and leggings, cropped sweatpants or distressed denims.
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Classically Chic
Reach for your knit or thin cotton hoodies (this might even just be a hooded top) to create a look that's smart casual and pretty. You'll want to layer the hoodie under a blazer and then pair with skinny pants and high heels. Large and bold accessories are an important finishing touch.
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References: yes-style