Could anyone explain how to do SEO audit

Selected answers from the Dumb SEO Questions Facebook & G+ community.

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  Michael Martinez: One of the purposes of an SEO audit is to learn about the site structure and composition. Every agency or consultant needs to audit the site when taking on a new client. There is no more efficient way to learn what the site is doing.
  
  So part of a complete auditing process is to document what the site is doing. Show the client you looked under the hood.
  
  But some audits are more targeted, needing less scope. For example, I`ve been asked to provide "second opinion" audits that only looked at certain aspects of Websites.
  
  Sometimes you only need to provide what people often call a "technical audit", which reviews how the site is coded and configured.
  
  Assuming you`re doing a full, 1st-time audit for a new client, you should look at everything you possibly.
  
  1. Their backlink reports (but don`t assume that every warning an SEO tool throws up about backlinks means something needs to be done) are a good place to start. You should try to determine if they have been buying links - especially if they haven`t said they`ve bought links. Clients sometimes conveniently forget thousands of links they paid for in the past.
  
  2. Their Bing Toolbox and/or Google Search Console query reports are also important. You should determine if there are opportunities for improving optimization for potentially valuable queries.
  
  3. Look at their page layout and try to determine if they creating "friction" in the user experience. Friction is anything that forces a visitor to take an extra action to accomplish a desired goal.
  
  4. See if they are publishing needless content. Don`t freak out over "duplicate content" - that`s often not a big problem. But if you find duplicate content and the site isn`t canonicalizing it properly, that`s something to report and suggest working on.
  
  5. See if they`re using "nofollow" on a lot of internal links (that`s usually a bad idea, unless they`re links to things like customer profiles, shopping carts, etc.).
  
  6. See if they`re using "noindex" on any pages. If they are, try to determine why. And if they are using "noindex", try to determine if it`s hurting the site`s crawlability (assume all the internal links on a "noindex" page are treated as "nofollow"). Sometimes noindexing content makes sense (maybe the pages aren`t ready for indexing); sometimes it`s harmful.
  
  ASK QUESTIONS. A good audit is honest. If you find something that doesn`t make sense, that doesn`t automatically mean it`s a problem. There may be (and usually is) a historical reason for why sites do weird things. The larger, more complicated a site becomes, the more likely someone will figure out a quick fix for a sticky problem - and that fix shows up in a future SEO audit.
  
  Your job as auditor is to understand what the site is doing, what potential value future SEO work can add to it, and whether the site has any real search-related issues that should be fixed. With 25, 000 pages of content you should not need to look hard to find opportunities for improving things.
  
  SEO auditing tools can only do so much of the work for you. The rest of the work must be done manually.
  
  
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  Shikha Shukla: Thanks Michael
  
  
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  Ash Nallawalla: Check the other tabs of Screaming Frog. How is the structured data, canonicals, performance etc?