1/ Paying too much!
Compare the 'cost per thousand' or use an expert media buyer, so that you know that you are getting good value for money.
2/ Getting the wrong coverage
Ensure that you are reaching your target audience.
3/ Using bad design and concepts
Make sure graphics are high quality so they look good both in colour and black and white, use a headline with powerful wording or a memorable graphic to capture attention and don't include too much text, as most readers will only scan your advertisement for the key information.
For more in depth information, please call Simon Grant on 01603 394959