What is a good and easy way for a 12-year-old to raise money?

See if your parent(s) are willing to have a garage sale. You could offer up to split the money in exchange for you running the sale.

or

Ask your parents for the money in exchange for a contract to do special things around the house.

or

I know it may seem way out there, but I also wanted to suggest you read an article I found for a self-made millionnaire (I like to think big):
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"Farrah Gray is known for being the youngest African-American to generate a million dollars in sales from a business venture. Gray has risen to national prominence in an American “rags-to-riches” story of success, perseverance and hard work.

Raised in the projects on Chicago’s south side, Gray defied the odds and became a self-made millionaire by the age of 14. Gray is one of the great business minds and icons of his generation.

Between the ages of 12 and 16 years old, Gray founded and operated business ventures that included KIDZTEL pre-paid phone cards, One Stop Mail Boxes & More franchise and The Teenscope “Youth AM/FM” interactive teen talk show, Gray was also Executive Producer of a comedy show on the Las Vegas Strip and owner of Farr-Out Foods, “Way-Out Food with a Twist,” aimed at youth familiar with the company’s first Strawberry-Vanilla syrup product. Farr-Out Foods “Foodfulooza” generated orders exceeding $1.5 million.

First Premiere Bank and Diamond Financial Products unveiled its newest debit card, The Farrah Gray Prepaid Mastercard®, which features Gray’s likeness on it. The “goFarr” card is designed to increase financial freedom and financial literacy.

Gray was also the youngest member of the “African-American Leadership” Roundtable invited by President Bush and the Director of the White House Office of Faith-Based and Community Initiatives, to set the stage for the upcoming corporate and philanthropic summit being planned for March 2006. Gray is renowned as the youngest African-American to rise from public assistance to business mogul without being in entertainment or having a family connection.

Gray is the author of “Reallionaire” which was nominated by NBC & Publishers Weekly Quill Awards in the category of "Health/Self-Improvement." His book appeared on Amazon and Barnes & Noble’s Bestseller List two weeks before its international release. “Reallionaire” was also named as the #1 Best selling Nonfiction Paperback Book in the August 2005 Issue of Essence Magazine.

Gray’s book and his journey to succeed against the odds have become required reading and part of classroom study from elementary school to entrepreneurship departments on college campuses. “Reallionaire” has been endorsed by former President Bill Clinton, Pierre Sutton, Stedman Graham, Jack Canfield and Mark Victor Hansen. Gray is also a Contributing Author to Chicken Soup for the African-American Soul.

He is an internationally known and respected entrepreneur and business leader who addresses more than half a million people per year on leadership, personal development, diversity, strategic planning, creativity, business development and financial management."
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I know this is a lot to read, but it's just food for thought...

The other jobs are OK, but why settle for 10 cents a newspaper? Just think about what it is you really want to do. This guy sold his mother's hand lotion (yes, a used bottle) and made a few dollars. Then he bought items from the store with that money to sell at a marked up price door-to-door again. Now he does what he really wants to in life, with all the money he made BEFORE he even finished high school. He could have retired at the age of 14 if he wanted to.

You could even ask your parents to "invest" in your business to cover starting costs, and they could get a percentage of your earnings in return (kind of like shares). This way, your parents know you are serious, and will be proud that you are trying to accomplish things on your own.

A lot of people out there may think this is a bit much for a 12 year old to absorb, but I choose to think that a 12 year old can have just as much potential as a 50 year old executive.

The important thing is, make sure you talk to your parent(s) first. They may want to set some guidelines for you (ie. make sure your grades don't fall).

Hope this helps.
Good Luck!