Things you always forget to do before Go Live but are very important. 

Data Import

Yes, it's prior to Go Live, but it's still important

• Ask Salesforce to turn on the ability to update System Fields
• Ask Salesforce to turn on Middle Name and Suffix fields.

Setup

Settings

• Turn off Advertising (UI)
• Turn off Quick Create

Sharing Rules

• Are Organizational Wide Defaults set for each object. 
• Have you finished your Sharing Rules setup. Does it cover all scenarios? 

Permissions / Profiles

• Ask Salesforce to turn on the ability for Admins to log in as all users
• Log in as each profile and test permissions
• Turn off access to Tabs and Apps that users will not use (it is to overwhelming for some users)
• Home page for each profile

Public Groups

• (Useful for Views permissions) Public Groups created

Public Site Settings

Eg for Public Knowledge Base, Payment Forms etc

• Does your public facing sites have the correct permissions - only minimum

Integration User

• Does your integration user only have the minimum required permissions

Chatter

• Any chatter groups created
• Any topics need creating

Objects

Views

• All required views created
  • Decide on which fields should be visible in each view
  • Set permissions for each view based on public groups

Record Types

• All objects have record types that are required. 
• Default record types are set for all objects - especially Opps

Page Layouts

• All Consistent
• All system fields down the bottom
• All headers consistent
• All workflow update fields set to be read-only
• Fields are hidden where necessary
• Feed views are created
  • Change Custom Buttons to Custom Links or hide Custom Buttons on Feed View
  • Each Feed View layout is exactly consistent
• Each user has the right layout

Search Layouts

• All Search Layouts Set
• Enhanced Search setup

Publisher Actions

Default

• Layout Set
• Any new actions created

Objects

• Each object has the right Actions

Reports

• Report folders created
• All Reports Created 
  • And filed in an appropriate folder
• Hide Unused Report Folders
• Create Report Types for custom objects if needed

Dashboards

• Dashboards created
• Dashboards running user set. 
• Dashboard on home page

Each User

• Install Salesforce for Outlook
• Set up Tabs
• Set up my email to Salesforce - make sure they have recorded it. 
• Unhide sidebar (or turn it off in Settings)
• Grant login to Admin for 1 year (if not set as default).