Outside of providing the explicitly stated deliverables in the SOW, these are the basic steps that should be completed during each project phase, unless there is a specific reason. All projects are a little different, but this is a good list of things to make sure of.
Prior to starting work, decide on a team for the project and ensure that the planned work fits their schedule.
Make sure the Site Documention gets updated by the artisan most responsible for the phase (ex. the lead designer)
At the end of each phase, make sure the relevant Project and Client database entries are up to date.
At the end of each phase, send out any invoices attached to that phase.
UX Phase (PM)
Have project QA engineer conduct an Accessibility audit on UX deliverables. This should happen prior to the client seeing the deliverables.
Visual Design Phase (PM)
Have project QA engineer conduct an Accessibility audit on the visual design. This should happen prior to the client seeing the deliverables.
Development Phase (PM)
Ensure the team completes standard, appropriate preflighting prior to QA (full list coming soon, use this for now)
Ensure that the QA engineer has all the details they need to perform a full QA on the site. If multiple QA passes are planned (ideally this should be clarified in the SOW), ensure that we perform the number that we stated.
QA Phase (PM)
Create a launch plan. Make sure that it is clear who will bear what responsibilities on launch day.