Search Engine Optimization (SEO) 
A helpful checklist / collection of Search Engine Optimization (SEO) tips and techniques.
Contents
- URL
- Accessibility
- Meta Information
- Keywords
- Content
- Images
- Videos
- Links
- Mobile
- Sitemap
- Social Media
- Tools & Services
- Webmasters
- Analytics
- Optimization
- Keywords
- Links
- Structured Data
- Bookmarklets
- Browser Extensions
- Jekyll Plugins
- TYPO3 Extensions
- WordPress Plugins
- Books
- Courses
URL
- Descriptive URLs: Use a descriptive page url, which should reflect your targeted keyword.
- File extension - Do not strip out the file extension on URLs.
- HTTPS - Security is a top priority for Google.
- Hyphens - Split words using hyphens.
- Localisation - Choose a country-specific domain, for better local search results.
- Subdomain or subfolder - Subdomains are seen as separate domains.
- URL builder - Use this tool to add custom campaign parameters to your URLs.
Accessibility
- 403: Provide a 403 - Access denied page.
- 404: Provide a 404 - Page not found page.
- Custom Search - With Google Sitelink search box, people can reach your content more quickly.
- File not found: Avoid
404 FILE_NOT_FOUNDerrors. - Layout: Use
divsinstead oftablesfor layout. Usingtablesis not semantically correct. - Moving a website: Redirect all your links to the new location via
.htaccess. - Pagination - Implement the
rel="next"andrel="prev"attributes to links. - Performance - Performance and loading time is important.
- Redirects: Avoid redirects if possible. Use 301 redirect instead of 302.
- RichSnippets - Markup your code with rich snippets, they show up on the search results page.
- Robots - Block pages which should not be indexed via the
robots.txtfile or<meta name="robots" content="">. - Validation: Write valid code (HTML Validator CSS Validator).
- WAI-Aria - Use WAI-Aria tags to help machines understand your code.
Meta Information
- Description - Each page should have a unique description (max. 160 characters)
<meta name="description" content="">. - Title: Each page should have a unique speaking title (60 - 100 characters)
<title>Website Title</title>.
Keywords
- Content: Keyword should appear in ~3% of article length.
- Heading: Keyword should appear in headings.
- Meta Tag - You can ommit the
<meta name="keywords" content="">, search engines do not use this meta tag. - Research: Rank for keywords with high traffic and less competition.
- Single: Every page should have a single unique targeted keyword.
- Title: Keyword should appear in page title.
- URL - Keyword should appear in URL name.
Content
- Content: Content matters the most in SEO.
- Flash: Avoid Flash content and Flash pages. They are not accessible on mobile phones and will be ranked lower.
- Freshness: New content is important. Updating pages or posting regularly is recommended.
- Headings: Clear structure
H1-H6max. 70 characters long. - Length: Article should be at least 300 words.
- Strong: Use
strongtag to highlight your targeted keyword. - Uniqueness - Do not provide duplicated content, use unique content types.
Images
- Alt tag - Add an alt-tag this a description of the image (60 - 70 characters).
- Dimensions: Add the
width=""andheight=""attributes to the image. - File name - Use a short descriptive name.
- Optimization - Optimize images by removing some meta information.
- Responsive Images - Serve the most optimized image corresponding to the window size.
- Size: keep the filesize as low as possible.