Using more keywords can generally lead to higher traffic volume, but you need to be careful. You want to make sure that the keywords you select are specific enough to your products or services and not too general. For example, if you sell only one particular brand of DVD player, you may not want to use the keyword, "DVD Players," because it would likely bring you traffic from users looking for DVD Players made by many companies.

Remember, you can use as many as 50 excluded keywords and 1,000 keywords per ad group. The Sponsored Search account interface allows you to add up to 500 keywords at a time. So, if you want to add the maximum 1,000 keywords, you’d have to add two separate lists of 500 keywords each.