I didn’t set it up, but we use Docusign then Zapier to automatically send a personalised Stripe invoice/payment link.
I think you can now do bank transfers via Stripe too but we take a credit card.
Docusign is good because they chase up (email automation) the prospect if they haven’t signed. Rather than you risking your relationship with them by following up.
I actually found the quickest way to speed up our payment process was a line from a training video in the Academy. I’m not sure which workshop but it was to ask about their “paperwork process”. Once you understand what that is, you can reverse engineer the quickest way to get through it.