One of the most common mistakes in marketing communications materials is forgetting to tell the reader, viewer, or listener what you want them to do. It happens all the time: someone crafts a brilliant, memorable message, but forgets to include some sort of instructions.
Do you want people to buy your product? Visit your website? If you don’t point them in the right direction, they’ll come up with a course of action on their own, and odds are good that it won’t be the one you intended.
Similarly, many ads and other materials fail to give the target audience a way to get in touch with the advertiser. There’s a tendency among many “creative” folks to think that such information is déclassé and uninviting, so they either minimize it or leave it out all together. Then, when someone is ready to buy or visit, they don’t know where to turn.
If you want people to take a particular course of action, tell them. And if you don’t want to do that, at least give them enough information so they can draw their own conclusions.