If you are sending a campaign to a particular email list or placing it on a specific Web site (vs. run of network), it's absolutely worth asking the list/site owner for creative and offer advice. We're about to launch an email campaign for a new Sherpa report to a partner's list, so I asked the partner if she had advice on what works for her audience.... and her reply made a huge difference.

For example, we were just going to include a link to our store page for the product, but she said about 20% of her list are more likely to order if we include a phone number, even though they may order on the site instead. She also advised us that her list prefer longer emailed letters than average. This type of advice is gold, and you can only get it if you ask for it. Funny thing is, according to list and media owners I chat with, hardly any marketers ever ask for it.