Create a pipeline whose stages reflect concrete customer decisions, then add a small sample of contacts and opportunities. Use the limited automation rules for the most repetitive follow-up actions rather than distributing them across marginal conveniences.
Bigin counts records across pipeline entries, contacts, companies, activities and notes, so monitor growth across the whole workspace. Keep the account active and export important information regularly. The free edition is a practical starting point for one owner rather than a multi-person sales team.