I once successfully closed a deal with a client because of sending a proposal that had a Service Agreeement and my Terms and Conditions attached.
If they approved the proposal, all they needed to do was sign the service agreement confirming they had read the Terms and Conditions and provide the requested info for the service agreement.
That way, there was no need for a second loop of reading contract and then signing.
This requires form fields, PDF attachments and a signature field at the end. But it speeds up the process and I'd love for that to be introduced here.