Starting a full-stack application can be a bit overwhelming, so it's important to approach it step by step. Here's a suggested sequence to kickstart your Task Manager application development:

### 1. Set Up Your Development Environment

Before you start coding, ensure your development environment is set up with all the necessary tools:

- **Code Editor**: Choose a code editor like VSCode, Sublime Text, or Atom.
- **Version Control**: Set up Git for version control.
- **Backend Setup**: Install Node.js and npm if you're using a Node.js framework like Express.js. For other backends, ensure you have the necessary runtime and package manager installed.
- **Frontend Setup**: If you're using a framework like React, Angular, or Vue.js, ensure you have the necessary CLI tools installed.
- **Database**: Install and set up your chosen database system (like PostgreSQL, MongoDB, etc.).

### 2. Initialize Your Project

- **Create a Git Repository**: Start by initializing a Git repository to track your project's changes.
- **Frontend Initialization**: Use the CLI tools (like `create-react-app`, `vue create`, or `ng new`) to generate the initial structure of your frontend application.
- **Backend Initialization**: Set up your backend project structure manually or using a framework-specific initializer.

### 3. Start with the Backend

- **Define Your Database Schema**: Plan and define your database schema, including tables/collections for tasks and potentially users.
- **Implement Basic CRUD Operations**: Develop the API endpoints to create, read, update, and delete tasks. Test these endpoints using tools like Postman or Insomnia.
- **Add Business Logic**: Implement the logic for handling task priorities and deadlines.

### 4. Develop the Frontend

- **Layout and Design**: Create the basic layout and design of your application. You might want to sketch or use a design tool to plan the UI.
- **Implement Task Display**: Develop components to display tasks in a list or grid.
- **Task Manipulation**: Implement forms and functionality to add, edit, and delete tasks.
- **Connect with Backend**: Use the services in your frontend to connect with the backend API and perform actual data operations.

### 5. Testing

- **Backend Testing**: Write tests for your API endpoints to ensure they behave as expected.
- **Frontend Testing**: Implement tests for your frontend components and functionality.

### 6. Iteration and Improvement

- **User Feedback**: If possible, get feedback on the usability of your application.
- **Refinement**: Refine and improve the UI/UX based on feedback.
- **Add Features**: Depending on your project's scope, you might want to add additional features like user authentication, notifications, or more advanced task filtering and sorting.

### 7. Deployment

- **Choose Deployment Platforms**: Decide on platforms for deploying your frontend and backend. Heroku, Netlify, Vercel, and AWS are popular choices.
- **Set Up CI/CD**: Configure continuous integration and continuous deployment to streamline your deployment process.

### 8. Documentation

- **Code Documentation**: Ensure your code is well-documented, making it easier for others (or yourself in the future) to understand and maintain it.
- **User Documentation**: Depending on your audience, you might need to create user guides or help documentation.

By following these steps, you'll have a structured approach to developing your full-stack Task Manager application, ensuring that you cover all necessary aspects from initialization to deployment.