Begin by accessing GitLab's REST API, which allows you to programmatically interact with your GitLab instance. You will need to generate a personal access token from your GitLab account to authenticate requests. Go to your GitLab profile settings, navigate to "Access Tokens," and create a token with the necessary API scopes, such as `read_api`.

Determine the specific data you wish to export from GitLab. This could include repositories, issues, merge requests, or project details. Identify the corresponding API endpoints needed to retrieve this data. For example, to get project data, use the endpoint: `https://gitlab.com/api/v4/projects`.

Use a programming language like Python to make HTTP requests to the GitLab API. Utilize libraries such as `requests` in Python to send GET requests to the identified endpoints. Ensure you include your personal access token in the request headers for authentication. For example:

```python
import requests

headers = {'PRIVATE-TOKEN': 'your_access_token'}
response = requests.get('https://gitlab.com/api/v4/projects', headers=headers)
data = response.json()
```

Once the data is fetched, it often comes in JSON format. Parse this JSON data to extract the relevant information you want to save in a CSV file. Use Python's built-in `json` library to handle this. For example, iterate over the JSON data to extract specific fields like project name, ID, or other relevant details.

Organize the parsed data into a tabular structure that can be written to a CSV file. Create a list of dictionaries where each dictionary represents a row, and keys are the column headers. This step ensures that your data is structured correctly before writing it to a CSV.

Use Python's `csv` module to write the structured data to a CSV file. Define the CSV file name and use a `csv.DictWriter` to write the data row by row. Specify the fieldnames that correspond to your CSV columns. Example code:

```python
import csv

fieldnames = ['project_id', 'project_name', 'description']
with open('gitlab_data.csv', mode='w', newline='') as file:
writer = csv.DictWriter(file, fieldnames=fieldnames)
writer.writeheader()
for item in data:
writer.writerow({'project_id': item['id'], 'project_name': item['name'], 'description': item['description']})
```

After writing the data to the CSV file, open the file to verify its integrity and ensure all data is correctly exported. Check for any anomalies or missing data. This step is crucial to confirm that the data has been accurately transferred from GitLab to the CSV file without any loss or corruption.

By following these steps, you can effectively move data from GitLab to a CSV file without the use of third-party connectors or integrations.