For a service business, the highest-value schema types are typically Organization (or LocalBusiness/ProfessionalService for location-based work), FAQPage for Q&A content, Service for each offering, and Article or WebPage markup on blog and answer content. Breadcrumb and Person schema for named experts round it out and support E-E-A-T signals.
Priority matters more than completeness — a well-tagged Organization plus FAQPage combination on your core pages typically does more for AI legibility than exhaustive markup applied inconsistently. Run pages through a validator before publishing, since broken schema can be worse than none.