You should test that, Chris Goward

Each website, each landing page, is built with an objective in mind, and often multiple objectives competing against each others. When the SEO has played its role and the visitors have landed on your page, how many of them meet these objectives, how many of them fill your form, order your product, share your content, convert?

In this book, Chris Goward explains with many case studies that the best practices recipes are just general recipes that need to be tested for each specific case. Even having some insights into how the human brain works through functional MRI or more classical user experience approaches, in the end, you have to measure the performance of your choices. In order to do so, the scientific approach is the most powerful: isolate one feature, challenge it with different versions in an A/B/n testing, and you will know what works best for your specific audience.

The conversion optimization process he presents starts with choosing what test page to prioritize, then how to establish hypotheses based on a series of factors: value proposition, relevance, clarity, anxiety, distraction, and urgency. The hypotheses have now to be tested, and the results analyzed.

You could simply choose a test page based on your gut intuition about which pages are the most important, or throw darts at your information architecture diagram, but by now I hope you realize that I'm going to recommend looking at some data to help you decide. Even with all the data available, some intuition is involved in prioritizing your test pages. Although the data may point to a problem in one area, the real problem can sometimes be at an earlier stage in the conversion funnel.
Fo example, I have often seen examples of high shopping-cart abandonment in e-commerce sites. In many cases, the problem can't be fixed on the shopping-cart page, though. Visitors are moving from the product detail pages and category pages into the cart to try to find the shipping and returns information, but that information should have been available on the product detail pages. You can often reduce shopping-cart abandonment by optimizing the earlier stages of the buying decision.

You should test that (Sybex editions, 2013, 360 pages), written by Chris Goward, founder and CEO of WiderFunnel, a conversion optimization agency based in Vancouver, Canada.