Ran into this article that warns "Don't Judge A Banner By Its' Cover" with nine helpful hints to keep your banner advertising fresh and relevant....
"1. Interact with your readers Banners and landing pages should be inviting and induce readers to click their way in. Users are drawn to well-designed, interactive banners that encourage them to take action. This increases the CTR (Click Through Rate) and contributes directly to the campaign's bottom line results.
2. Diversify design and approach It is best to prepare several sets of banners with different color palettes and designs so that effective testing and evaluation can be conducted throughout the campaign. Different designs, colors, platforms and sizes yield different results - so several approaches should be tried and tested. Also, this enables banners to be tested across several different sites. All these parameters should be evaluated thoroughly so that the results can be used intelligently to boost the bottom line.
3. Don't judge a banner by its cover A good banner is not necessarily the most "attractive." In online advertising "artwork" is judged by what works to get the reader to do what you want. Your banner doesn't have to win a design award or hang in an art museum to work for you. Remember: the focus is on measurable results.
4. Match the creative to the payment model Again, always focus on the goal. Creative content must be adapted to the user and provide the relevant information needed to achieve the business objective.
For example, on CPC campaigns we want to better qualify clicks. If you use a CPC (Cost-per-Click) campaign to sell tickets to a concert, then the banner should not maximize clicks but rather offer relevant information toward purchasing tickets - making the clicks are effective. Perhaps the CTR of that campaign will be lower than if the banner said "For more information on the concert, click here" instead of "Best concert in town - click here to get your ticket." But based on the payment model chosen, it is the right choice. If the CPA (Cost-per-Action) or CPL (Cost-per-Lead) models were being used, a combination of banners with different content may prove to be more effective.
5. Focus on the conversion Don't be fooled into thinking that the CTR is a direct reflection of the conversion rate. High CTR maybe not mean a successful campaign and a low CTR may not mean it was unsuccessful. For example, if a bank looking for new business posts a banner with a really sexy image, it will probably draw a lot of hits to the new account landing page. The bank may get a high CTR, but how many accounts will be opened? Remember: in the end it is the conversion that counts.
6. Speak in multiple languages Speak to the audience -- literally -- by making sure the language and call to action in the banners and landing pages are suitable to local audiences - where campaigns are running and culturally attuned to the audience. On the other hand, it is worthwhile to try banners in different languages to make them stand out on the page. For example, on a site that is completely in Spanish, an English banner may in fact draw more attention.
This is yet another measure that can help you improve and perfect banners based on the results you measure throughout the campaign.
7. Call users to action Well-placed keywords that call the user to action have a better chance of directing users to your landing page - and leave nothing to guesswork. Clear instructions, like "click here," "continue," or "register" help to lead users along the path you determine.
8. Set specific and predetermined time periods Time-limited offers and promotions are an effective way to invite the user toward the action you wish and can compel users to respond faster. For example, establish a "count down" period that the offer is valid, or eligibility for a certain prize or gift.
9. Keep it new and enticing Be bold. Don't be afraid to try something you have never tried before, rather that sticking with something that everyone liked and never change it. Old banners become background very fast, and stop standing out on the page. Upgrade and change them regularly to keep it new and keep it changing. Innovation is part of the game. These tips are a good starting point to keeping your online advertising creative up to date, relevant and targeted on results. And a great way to be sure you are maximizing your online advertising investment"
All of these are great tips that can help you with a client campaign as you can use it for a template to create the key elements used in the campaign.