I am not an ad expert, but I can tell what I believe makes an ad creative and famous. First thing is to determine who you want your target audience to be. If you trying to advertise kids cereal, cartoon characters are probably the best way to go. Examples Tony the Tiger, Captain Crunch, Snap Crackle and Pop. I also notice that establishing characters helps people to remember a commercial. Examples like Flo from the Progressive commercial, the Gecko lizard from the Geico commercial, and the Aflec duck. I also notice that creating a simple slogan makes an ad memorable. Example Burger King had Have it Your Way, Allstate has You're in Good Hands, Pepsi had Pepsi The New Generation, the NBA had NBA It's Fantastic, Wendy's had Where's The Beef. Obviously comedy will make an ad very memorable. Commercials that make you laugh stays with you.