Begin by creating a Slack app in the Slack API portal. Navigate to the Slack API website, sign in, and create a new app. This app will be used to interact with Slack's APIs. Once created, note down the Client ID, Client Secret, and Signing Secret, as these will be required for authentication later.

Define the appropriate permissions to access the data you need from Slack. For instance, if you want to read messages from a channel, add the `channels:history` permission. Go to the "OAuth & Permissions" section in your Slack app settings and add the required scopes. Install the app to your Slack workspace to apply these permissions.

Prepare your AWS environment to accommodate DynamoDB. Log into the AWS Management Console, navigate to DynamoDB, and create a new table. Define the primary key to suit the structure of the data you are planning to store. Ensure that you have the necessary AWS IAM roles and permissions to read and write to DynamoDB from your application.

Write a script in a programming language like Python or Node.js to fetch data from Slack. Use Slack's Web API to retrieve the necessary data, such as messages, user information, or channel details. Authenticate your requests using the OAuth token obtained when installing your Slack app. For example, use Python's `requests` library to make HTTP requests to Slack's API endpoints.

Once you have fetched the data from Slack, parse it into a suitable format for DynamoDB. This might involve converting JSON data into a dictionary or list of dictionaries, ensuring the data types align with those supported by DynamoDB (e.g., strings, numbers, and lists). This step may require flattening nested structures or converting timestamps to a consistent format.

Implement logic in your script to write the parsed data to DynamoDB. Use AWS SDKs such as Boto3 for Python or AWS SDK for JavaScript to interact with DynamoDB. Construct `PutItem` requests for each record you want to insert. Ensure your script handles potential errors or exceptions, such as duplicate key errors or network issues, and implements retries or logging as necessary.

Set up a system to automate the data transfer process. You can use cron jobs on a server to run your script at regular intervals or leverage AWS services like Lambda and CloudWatch Events to trigger the script execution. Ensure your automation solution includes logging and error handling to monitor the process and troubleshoot any issues that arise.

This guide provides a straightforward approach to moving data from Slack to DynamoDB using custom scripting and AWS services, without relying on third-party connectors.