What I've seen work best is a short list, not a big system. Every quote that's still open two business days after you sent it goes on one list: name, job, date sent, next action. Day 2: one short text — 'just checking the quote came through OK, any questions?' Day 7: one more, with something useful in it, not just 'checking in.' Day 10–14: a closing message — 'should I keep this open or close it for now?' — then archive it and move on. The part that makes it stick is a 15-minute end-of-day sweep: scan the open quotes, send the ones that are due, and nothing sits overnight without a next action or an exit date. And put a real expiry date on every quote when you send it — it gives you an honest reason to follow up, and stops the list growing forever.
