A study abroad program is going to take you to far away places, so that means you'll be without the everyday things that are always within your reach.
So when you decide to pack you need to make sure you have the essentials that will make your study abroad experience an enjoyable one.
The most important thing you can do is to pack the bare minimum because you don't want to be hauling around tons of luggage everywhere you go! And always label your luggage with your name, address and telephone number in case it gets lost.
Listed below are some general items to pack no matter what location you visit.
Carry-On Luggage Always pack your most important items in your carry-on luggage so they won't get out of your sight!

Your passport, VISA, travel itineraries and other important documents

Travel guides and maps of your host country

Calling cards and your cell phone

Any valuables such as jewelry, a laptop, credit cards, check book, cash, iPod, traveler's checks, camera, etc.

A change of clothes and a toothbrush (just in case your larger luggage gets lost)

Clothing The type of clothing you pack will depend largely on the country that you visit, so dress accordingly.

1 warm coat/jacket

10 shirts (mixture of t-shirts, sweaters, blouses)

1 nice suit/dress outfit for special events

2 pairs of jeans

2 pairs of shorts

1 pair of sweat pants

1 belt

1 bathing suit

10 pairs of socks and underwear

1 pair of dress shoes

1 pair of sandals/flip-flops

1 comfortable pair of sneakers

Toiletries Most toiletries can be purchased overseas, so pack only the name brand items that you think will be hard to get abroad.

Comb/brush

Toothbrush/toothpaste

Lotion

Deodorant

Glasses/contact lenses (with contact solution and carry case)

Any personal medication

Shampoo/conditioner

A small personal hairdryer

Towels

Miscellaneous There are always random items that you should bring that will help you when you explore your host country.

Sun glasses

Umbrella

Travel alarm clock

Journal

Flashlight

Bug spray

Extra batteries

Language dictionary

Personal sewing kit

If you plan on making many day trips to places in your host country then make sure that you bring a good-sized backpack to fit all your necessary items in it.
Also, if you know that you'll need school supplies, check first with your study abroad program to see if they provide supplies.
That will be less paper and bulk for you to carry as you travel.
And the less that you pack the more time you will have to travel quickly to different destinations!