This post was originally published October 17, 2013 and has since been updated for accuracy and freshness.

Redesigning your website can feel like walking into a minefield in terms of search engine optimization. Worst case scenario, you could lose all your search engine rankings and have to start from scratch. Fortunately, this doesn’t have to happen--if you do the transition the right way.

While human users are, of course, always your first priority, it’s important to remember that search engines are also a key part of your website target audience. Make it easy for search engines to recognize the changes you've made including domain, site structure, links, and so on. SEO planning and attention early in the process increases the chances that you complete the transition without dropping in search results. You might even come out ahead.

Bear these nine factors in mind to keep search engine rankings riding high, even during a redesign.

1. Redirects

If your new website involves a new set of URLs, 301 redirects are a must-have. 301 redirects inform search engines that the content has permanently moved to a new location. This way the search engines know that the new pages have the same or similar content, and that it's safe to assign the existing rank to the new page. This is also the case even if you’ve only changed the extension, such as changing "http://example.com/default.html" to "http://example.com/default.aspx".

It’s vital that every page on the old website is set up with its own 301 redirect both for SEO purposes and to keep your visitors from running into broken links. Some site owners try the shortcut of setting up a general redirect that funnels all the old pages to the homepage of the new website, but this will annoy users and search engines alike. If it isn't possible to do a one-to-one match between old and new pages, you should at least have the old pages point to a new page with similar content. If this isn't possible to do automatically, and you have too many pages to redirect manually, at the very least, be sure to set up 301 redirects for your most important and most visited pages.

2. Change of Domains

If the transition from the old website to the new website includes a change of domain name, consider breaking the process down into two separate steps. First, move the old website to the new domain, setting up 301 redirects for each page on a one-to-one basis. After this is done, launch the new website on the new domain and double check that the redirects are correct. This will minimize the risk of something going wrong in the process.

3. Backlinks

Collect the stats of referring links to your website (backlinks) and identify the most popular of these. This information can typically be found in an analytics or SEO tool, such as Siteimprove SEO. Ideally, you would contact the owners of all referring websites and have them change the link to point to your new page, but this isn't practically possible. Alternatively, try contacting the owners of the most popular backlinks and have these changed. Then make sure that the pages that the rest of the backlinks point to are properly 301 redirected.

4. Page Titles and Meta Descriptions

Make sure that all pages on the new website have page titles and meta descriptions. You can transfer these from the old website--if (and only if!) they are unique and descriptive of the page content. If your titles and descriptions aren’t up to par, a redesign is a great opportunity to focus on creating more search engine-friendly meta content.

5. Sitemaps

When you launch your new website it's a good idea to have two complete sitemaps configured: an HTML sitemap for users and search engines, and an XML sitemap for search engines only. An XML sitemap helps search engines crawl and index your website faster. You can submit an XML map to search engines like Google and Bing through their webmaster tools.

6. 404 Page Not Found

Although you want as few visitors as possible to see it, a 404 error page that’s both user and search engine-friendly is an important element. Even if you've created 301 redirects for all content on your old website, the odds are that users are still going to come across broken links from time to time. A good 404 page will help the users and search engines get back on track in an easy way via useful links, a search box, or at the very least a redirect to the homepage. It is also a good idea to keep the menu of the website on the 404 page for increased usability.

Besides having a user friendly 404 page, it’s also important to make sure that the page actually returns HTTP code 404 so search engines are made aware that they followed a broken link. You should also ensure that you have tracking on your 404 page, so you can identify the referrers and fix the broken links. If you aren't careful, you could end up having the 404 page being one of the most visited pages on your new website.

7. Robots.txt

Review and update your robots.txt file if you have one on your old website. The robots.txt file is used to inform search engines about pages you don't want crawled and/or indexed. This should be updated to match your new URL structure.

It's also important to make sure that any development or test websites aren't crawled as this can result in duplicate content issues. In this case, it's a good idea to use robots.txt to block the search engines and at the same time add password protection as an extra level of security.

8. Avoid broken links

Use a quality assurance tool such as Siteimprove Quality Assurance to ensure that there are no broken links on the website. Even though you've set up 301 redirects for all your old content, problems can still arise, especially if some of the old pages employ absolute URLs in the links instead of relative URLs (e.g. "http://example.com/users/foo.aspx" vs. "/users/foo.aspx").

9. Transition Period

Last but not least, if you’ve changed your domain name, Google recommends that you keep the old domain name with the 301 redirects for at least 180 days as a period of transition using the change of address tool. This gives Google’s bots ample time to crawl and index all your new pages. If you follow these nine simple tips you minimize the risk of your website disappearing from search rankings in the transition. Make a point of approaching search engine optimization as part of the brainstorming and design phase when you start your new website project. Your plan is to end up with a shiny new website, regardless. Why not make it search engine friendly from the start?

Download the e-book: How to Prepare for a Website Redesign