When it comes to SEO it's a little bit of a black-art, but there are some established "best-practices" that can potentially help creating a website for your business and achieve a better SERP. Here is a quick list and some tools to help with that analysis.

Very helpful cheatsheet the Mozilla Developer Network (MDN)!
Great SEO Toolkit SEOChat

• Back Links
  • INFO/TOOLS: Google's Search Operators. Example: "link:"
• PR Ranking
  • TOOL: PR Checker
• Keywords
  • TOOL: SEM Rush
• Microdata/RDFa
  • INFO: Google - Structured Data
  • TOOL: Structured Data Testing Tool
  • INFO: Schema.org
• Clean, semantic markup. Text-to-code ratio. Correct use of H1,H2 tags. Image alt and anchor tag title attributes
  • INFO: http://www.sitepoint.com/text-to-code-ratio/
  • TOOL: Code to Text Ratio
  • TOOL: DOM Monster - Javascriptlet
• Descriptive, Contextual content
• Sitemap.xml
  • sitemaps.org
  • TOOL: Sitemap Checker

Ever wonder how some Google SERP listings have a search box included in their listing? Example: Google "php.net" and note that their listing has a search box included.

Turns out to be pretty simple to implement; weather Google pick up on, and choose to include it is a different story :-)

https://developers.google.com/structured-data/slsb-overview

In a post to the Official Google Blog on Feb 26th (2015), Google announced:

"Starting April 21, we will be expanding our use of mobile-friendliness as a ranking signal. This change will affect mobile searches in all languages worldwide and will have a significant impact in our search results. Consequently, users will find it easier to get relevant, high quality search results that are optimized for their devices."

"Mobile Friendly" is now amongst the SEO algorithm mix along with Structured Data ("Rich Snippets").

Here are a list of useful tools/websites to help you check your current Mobile/Structured Data performance:

• Google Tool: Mobile Friendly Testing Tool
• Google Tool: Mobile Usability Tool
• Google Tool: Rich Snippet Testing Tool
• Google Mobile Guide - Getting Started

Original article: http://thenextweb.com/insider/2015/02/26/google-will-rank-your-site-higher-if-its-mobile-friendly-starting-april-21/