Just because the potential customer has initiated the final processes does not mean you should be letting off the gas. You want to do what you can to keep them engaged and willing to finalize their decision.
Automation and customer relationship management (CRM) integrations are going to be an integral part of this step. CRM will keep that line of communication open and seamless. This can help avoid hiccups that might have them turn away before making their final decision.
Be active and visible. Invite them to join and participate in webinars that you plan to hold. If this is something that can fit your business model, it can be wonderful for getting them to move over that final step.