Which ideas should I rate?

The more the better!
Rate the ideas you like and the ones you don't like that much - you've got the whole scale from 1 to 10 at your hands. This way, subjective preferences are evened out and it becomes apparent which idea is preferred by the majority of users.

Even if you didn't submit an idea in a project, rate away. jovoto is based on a lively exchange of opinions between the creatives. Therefore, it’s important that the creatives assess the quality of an idea by rating it. The rating provides feedback for the creator of an idea and helps with the creative process.

There's one exception: don'r rate ideas of friends when you feel like you can't stay objective!