There are several popular scales used in questionnaire design including Likert and semantic differential scales.
General guidelines
Google Surveys lets you choose from 5, 7, 10, or 11 stars. There has been a long-lasting debate between 5-pt vs. 7-pt and odd vs. even (see presentation). As our surveys are easy to copy and easy to deploy, a good practice is to run the same question with a couple alternative scales. This lets you validate and cross-tabulate the results. It also lets you test a couple dimensions at the same time (e.g., both affective and cognitive responses to content).