Begin by logging into your ConvertKit account. Navigate to the subscriber list or campaign you wish to export. Use the export feature provided by ConvertKit to download your data in a CSV format. This file will contain all the necessary data you want to transfer to DuckDB.

Ensure you have DuckDB installed on your local machine. You can download it from the official DuckDB website and follow the setup instructions for your operating system. Having a working environment ready is crucial for the next steps.

Open the exported CSV file using a spreadsheet application like Excel or Google Sheets. Inspect the data for any inconsistencies or errors, such as missing values or incorrect formats. Clean the data by correcting these issues, ensuring it's ready for a seamless import into DuckDB.

Open a terminal or command prompt and launch DuckDB. Create a new database by entering the command:
```
duckdb my_database.db
```
Replace `my_database.db` with your preferred database name. This command initializes a new DuckDB instance where you will load your data.

Decide on the structure of the table that will store your CSV data. Define the table schema based on the columns present in your CSV file. In the DuckDB shell, execute a `CREATE TABLE` statement to define this schema. For example:
```sql
CREATE TABLE subscribers (
id INTEGER,
email VARCHAR,
name VARCHAR,
signup_date DATE
);
```
Modify the column names and types according to your CSV file's structure.

Use the `COPY` command in DuckDB to load the data from the CSV file into the newly created table. Run the following command:
```sql
COPY subscribers FROM 'path/to/your/exported_file.csv' (AUTO_DETECT TRUE);
```
Replace `'path/to/your/exported_file.csv'` with the actual path to your CSV file. The `AUTO_DETECT TRUE` option helps DuckDB automatically determine the delimiter and other properties of your CSV.

Once the data is loaded, verify the import by running basic SQL queries to count rows or fetch a few records:
```sql
SELECT COUNT(*) FROM subscribers;
SELECT * FROM subscribers LIMIT 10;
```
These queries will help confirm that the data has been imported correctly and is ready for further analysis or manipulation.

By following these steps, you can successfully move data from ConvertKit to DuckDB without using any third-party connectors or integrations.