If you are a Jewish boy, you can accomplish two things by picking as your informative speech topic the ritual of the Bar Mitzvah. You can make this an easy topic because you will have already gone through it and, therefore, have all the information you need. You can also make this speech interesting if your audience is not familiar with Jewish religious rites.
Informing your audience about your favorite musical style, artist or band should be one of the easiest speeches you'll ever give. Research will probably be next to nothing since you have likely already accomplished that for non-studious reasons. Giving this speech should also be more comfortable for you since are already somewhat of an expert on the topic.
An informative speech does not necessarily have to become an exercise in how to do something, but choosing this approach can make it an easy speech for you. Consider the things you already know how to do, and craft a speech around that. To make this a truly easy informative speech to give, don't limit yourself to what you do that is difficult. A how-to informative speech can range from how to crack eggs when making an omelet to how to pick out shoes that match your dress.
Another way to make writing and giving an informative speech easy is take personal experience and use it as a way to comment on a larger topic that would require far more research. Inform you audience about the existence of ghosts by writing a speech that explains your mysterious encounter with the paranormal. Offer information about how some of your dreams have seemed to come true as a way of touching up the subject of dream meanings.
By the time you reach a point where you will be called upon to give an informative speech, you will doubtlessly have created a history of getting at least temporarily interested in something yourself. Look back at your own life for things you have collected at one time or another that would make easy informative speech topics. Consider what you know about comic books, Barbie dolls, life as a military brat, muscle cars, Saturday morning cartoons or the most delicious boxed cereal ever made.