Here is a great article from  New York Conservatory of the Dramatic Arts.

COMMERCIAL ACTING

When acting in a television commercial, remember that you are there to sell a product. In these instances, it is not so important to have motivation for your character, do a detailed breakdown of his/her character. Instead, focus on the product you are promoting; it is the star.

If you are reading your own copy, be sure to give a little more emphasis to the name of the product or service. This technique can be called either “punching” or “warming” a word or phrase, depending on the mood of the ad. Be sure not to overdo it. Advertising is a subtle art. You want the audience to believe you, not feel pressured by you.

    The New York Conservatory of the Dramatic Arts