Begin by ensuring your environment is set up correctly. Install Python on your system if it isn't already installed. You will also need `pandas` for handling CSV data and `pymongo` for MongoDB interactions. You can install these using pip:
```
pip install pandas pymongo
```

Make sure your CSV file is formatted correctly. Check that the first row contains headers that describe the data in each column. Remove any unnecessary quotes or special characters in the data that might cause issues when reading the file.

Use pandas to load the CSV file into a DataFrame, which is a convenient data structure for handling tabular data. Here is an example code snippet:
```python
import pandas as pd

csv_file_path = 'path/to/your/file.csv'
data_frame = pd.read_csv(csv_file_path)
```

Ensure MongoDB is installed and running on your local machine or a server. You can download MongoDB from its official website and follow the installation instructions for your operating system. Start the MongoDB service once installed:
- For Windows: `net start MongoDB`
- For macOS/Linux: `sudo service mongod start`

Use pymongo to establish a connection to your MongoDB instance. Specify the database and collection where you want to store your data. Example:
```python
from pymongo import MongoClient

client = MongoClient('localhost', 27017)
db = client['your_database_name']
collection = db['your_collection_name']
```

Convert the pandas DataFrame to a list of dictionaries (JSON-like format) which can be inserted into MongoDB. This can be done using the `to_dict()` method:
```python
data_dict = data_frame.to_dict(orient='records')
```

Finally, insert the data into your specified MongoDB collection using the `insert_many()` method. This will upload all records from the list to your database:
```python
collection.insert_many(data_dict)
```
Verify that the data has been inserted successfully by checking the collection within the MongoDB shell or a GUI client.

By following these steps, you can efficiently transfer data from a CSV file into a MongoDB database without relying on third-party connectors or integrations.