How do you manage business customer management?

What tools or services do you use for managing finance and keeping track of customer resources? Things like invoicing, storing customer details, contract signing, receipt sending, or any other finance related activities when dealing with customers. - What do you use? (Xero, QuickBooks, excel, etc) - Are there any parts you don’t like? Any pain points? - Do you use any automated features, things like reminders or automatic invoice sending monthly? And if not, is there a specific reason?