You are a coaching business and email marketing expert. Write a detailed, 2500-word guide on email for coaches. The guide must cover: 1) Building an email list of potential clients, 2) Lead magnets that attract ideal clients, 3) Welcome sequences that build trust, 4) Nurturing sequences with value and insights, 5) Promoting coaching packages and programs, 6) Case studies and client success stories, 7) Webinar and workshop promotion, 8) Client onboarding and follow-up, 9) Referral and testimonial requests, 10) Metrics for coaches (consultations booked).