I think we all find it difficult at times because of the speed we move at in eCommerce. Often the first element that falls off is the simplification of the creative assets on our site. Consumers are looking for quick navigation and need to understand what they are getting in return for continuing their journey through the site.
Try and keep everything at a basic level and remove your understanding of the event / promo or site when designing your site assets. If you want a consumer to click on an ad unit in your site you need to give them a reason why, but at the same time not provide too much information, decisions are made in seconds and landing pages can be used to continue the conversation.
By no means is this an easy task but it is essential if you want to improve your site conversion, sales and consumer engagement. The easiest way to start is to take a step back and ask the question "If I was new to this site what am I expecting to get if I click on this link or ad?" If you can't answer this question by looking at the creative assets / message or the answer is I'm not sure then go back to the drawing board and make some changes. Remember consumers don't need to use your site so make it a positive experience for them.