The main mistakes that should be avoided are filling keywords in webpage, employing identical anchor text for link building, keyword stuffing, getting low quality backlinks etc
The names of a few SEO tools are Google Webmaster Tools, Google Analytics, Google Keyword Planner, Buzzsumo, Bing Webmaster Tools, SEMRush, Check My Links etc.
Rand Fishkin is the CEO and Co founder of Seomoz, the most popular seo software in the world. He started the informative "White Board Friday" series for explaining the concepts related to Seo and search engines.