Flutter Invoicing App Development

I'm looking for "one" Flutter developer to build a new invoicing app. This project will require refactoring an existing app which has required Firebase scaffolding. Key features of the app will include:

- Quote-to-Invoice Conversion: Craft detailed quotes outlining payment terms and deliverables, automatically converting approved quotes into professional invoices. It should include customizable templates and automatic tax calculations.
- Time and Expense Tracking: Track project hours and billable expenses, converting them directly into invoices for precise and transparent billing.
- Automated Payment Reminders & Customer Portal: Send payment reminders, and allow customers to access quotes, invoices, and statements through a secure customer portal.The app should support various payment methods including Credit/Debit Card, PayPal, Venmo and Zelle for the automated payment reminders.

Ideal skills and experience for this job include:
- Strong proficiency in Flutter
- Experience with Firebase
- Understanding of invoicing and payment systems
- Knowledge of implementing automatic tax calculations
- ASO

- keyword research for optimal app store and play store visibility
    
- Implement on-metadata optimizations, including title, subtitle, and description enhancements
    
- Develop a strategic plan for acquiring positive reviews and high ratings
      
- Achieve targeted keyword installs to enhance organic visibility and user acquisition

In your proposal, please mention your most recent ASO experience as well and how you'll tackle it for this project.