Many people wonder if they have to do much advertising at once or over a rather long period. In fact, it depends on the products you sell or services you offer. If you do a special promotion on a product, you should use adwords on a short time in mentioning this particular product over your business. If you cons want to sell your products over a long period and be known, your campaign should be long term. The same principle applies if you offer a service. You should use Adwords Editor to help you and of course this site.