Build 404 Page http://www.impactbnd.com/blog/how-to-improve-your-404-pages-delight-visitors

Make sure that a Favicon is present. 

BrowserStack IE/Mobile Test

https://www.browserstack.com/users/sign_in
internal@lean-labs.com
Hawkman5252*

Key Page Speed Test (Under 2 Seconds) - http://tools.pingdom.com/fpt/

Insert Analytics / Retargeting Pixel / HotJar

Sitemap, Robots.txt, Check Meta Data

Complete Final Amends (If applicable) 

White Glove Amends (1h Max) 

Do your happy dance, Drink a beer (Maybe Both)

Setting up 404 Event Tracking - https://www.useloom.com/share/94ed738cd8aa42da8f17b72e6b103f6d

Setup Email Sending Domains for DKIM  How to set up your email sending domains

Setup 301 Redirect from the non-www version of the domain to the www version via the DNS provider. More Info...

Meta Tags: address meta tags for key pages first, then as time allows, do all pages in footer of website.

Google Webmaster Tools: add the site, which includes verifying with a header code, and then loading the sitemaps.