Begin by ensuring your development environment is ready. Install Python, as it will be used to write the script for fetching data from CoinMarketCap and storing it in Redis. Make sure you have access to a Redis server. You can install Redis locally or use a cloud-based Redis solution.

To interact with CoinMarketCap, you need an API key. Create an account on the CoinMarketCap website and navigate to the API section. Select a plan that suits your needs and generate an API key. This key will be used to authenticate your requests to CoinMarketCap's API.

Install the necessary Python packages using pip. You'll need `requests` for making HTTP requests to the CoinMarketCap API and `redis` for interacting with your Redis database. Run the following commands:
```bash
pip install requests
pip install redis
```

Write a Python script to query the CoinMarketCap API and fetch the desired data. Use the `requests` library to make GET requests to the API endpoint. Here’s a basic example:
```python
import requests

api_key = 'YOUR_COINMARKETCAP_API_KEY'
url = 'https://pro-api.coinmarketcap.com/v1/cryptocurrency/listings/latest'
headers = {
'Accepts': 'application/json',
'X-CMC_PRO_API_KEY': api_key,
}

response = requests.get(url, headers=headers)
data = response.json()

# Process the data as needed
```

After fetching the data, you may need to process or transform it before storing it in Redis. This could involve extracting specific fields, formatting data, or performing calculations. Ensure that the data structure you prepare is suitable for your Redis database schema.

Use the `redis` Python package to connect to your Redis server and store the processed data. Here’s a simple example of how to connect and set data:
```python
import redis

# Connect to Redis
r = redis.StrictRedis(host='localhost', port=6379, db=0)

# Store data in Redis
for item in data['data']:
r.set(item['id'], str(item))
```
Ensure you replace `'localhost'` and `6379` with your Redis server’s actual host and port if different.

To keep your Redis database updated with the latest data from CoinMarketCap, schedule regular intervals for your script to run. You can use a task scheduler like `cron` on Unix-based systems or Task Scheduler on Windows to automate the script execution. Ensure the frequency matches your requirements without exceeding CoinMarketCap API rate limits.

By following these steps, you can efficiently transfer data from CoinMarketCap to Redis using a custom script without relying on third-party connectors or integrations.