You have to start with a wireframe that allows you to organize and control content and placement a lot better, and in turn that helps the end user flow more freely and get a better experience.
Also, designing the right graphics and images will help you get better results when it comes to visual aspect and time spent on that page.
Think about what media you want to play inside of your website and where to place that media for the best results with end user.
Think about having drop down menus if you have multiple categories in your industry and how to list them properly.
Have external css, no inline that will give you more control as well for your stylization and will allow you to use cascading styles to have all pages follow the master page for faster implementation and development.
Have a very detailed “About” page that goes over your history, goals, and what makes you stand out from the rest of your competitors.
Build the website with strong SEO in mind and set all Meta and internal links to be crawled more easily and rank higher.
Watch using to many plug-ins, as they create security holes and can prolong loading time.
Make sure all text is properly displayed and controlled from a well-read stand point.
Also make sure H1 and all tags are described right and reflect keywords, but watch the character count.
Get social traction into your website by means of clickable links, a “like” button, etc.
Make sure there is a site map and xml/kml file for your website. I personally like LXR Marketplace for XML Sitemap generation.
Have the proper amount of pages and have navigation to and from each page
Link your Google plus page to your website and your website to your Google plus page for Authorship credit.
Make sure your client, if any, is staying in contact on the design and overall concept from the beginning.
Optimize and alt tag all pictures.
Try to incorporate a contact form, Goggle maps, and strong linking factors on your pages.
Stay away from flash (I recommend Java), Google is getting more involved with Java Script and how it’s used.
Try to build content that people will want to link to or from so you don’t have to do too many link submissions.
Have a client testimonial page.
Maintain and keep up to date with the inner workings of your website keep it managed always!