• Start at Seller University, there is tons of great information from best practices for product detail pages to information about promoting your products.
• Visit Seller Central Help for resources on all topics, but take a look at this one about increasing sales.
• You can visit the Selling Partner Appstore and the Amazon Verified Partner Directory if you're looking for tools, apps, and partners to help with all aspects of your selling business, including product detail page enhancement and maintenance.

However, the best advice I can give you is to think like a customer. When it comes to e-commerce, you have to remember that the product is not physically in front your consumer nor is there a sales associate there to help. Approach your detail pages like they are a physical store.

• Ensure all the information you would find on a physical product is present (e.g. sizing, fabric, size charts, fit information, color, etc.).
• Merchandise your page so it's appealing to customers just as a store would merchandise physical product to entice customers browsing a store. Ensure your product images are clear and high quality. Provide different angles of the product so customers can "inspect" it like they would in a store.
• Create a voice for your brand to build trust in your products. Register for brand registry. Create A+ content that has lifestyle images of the product and provides extra detail that you might get from a Sales Associate in a store. Create a Store for your brand so your customers can browse other products sold by you.