Begin by exporting the necessary data from Pivotal Tracker. Log in to your Pivotal Tracker account, navigate to the project whose data you wish to export, and use the built-in export feature to download the data. Pivotal Tracker typically allows you to export data in CSV format, which is suitable for broad compatibility and ease of use.

Once the data is exported, inspect the CSV files to ensure that they are correctly formatted and contain all necessary information. Check for any inconsistencies or missing data that might need to be addressed before importing into Snowflake. Clean up the data as needed by removing duplicates, correcting errors, and ensuring uniformity in data types.

Access your Snowflake account and prepare the environment for data import. This involves creating a new database and schema if they do not already exist. Use the Snowflake user interface or SQL commands to create a suitable structure that will accommodate the incoming data.

Create tables in Snowflake that correspond to the structure of your CSV data. Define the tables with the appropriate columns and data types that match the information in your CSV files. Ensure that the table schema aligns with the data format to avoid any compatibility issues during the import process.

Use the Snowflake web interface or command-line tool to upload the CSV files to a staging area in Snowflake. This is a temporary storage area where files are kept before being loaded into tables. Use the `PUT` command to transfer your files to the Snowflake stage. For example:
```sql
PUT file://path/to/your/csvfile.csv @your_stage;
```

Load the CSV data from the staging area into the Snowflake tables using the `COPY INTO` command. This command reads the data from the stage and inserts it into the specified table. Ensure that you handle any potential errors or data type mismatches during this process. A basic example command is:
```sql
COPY INTO your_table
FROM @your_stage/your_csvfile.csv
FILE_FORMAT = (TYPE = 'CSV' FIELD_OPTIONALLY_ENCLOSED_BY = '"');
```

After loading the data, verify and validate that the data in Snowflake matches the original data from Pivotal Tracker. Execute queries to check for data consistency, completeness, and accuracy. Address any discrepancies by troubleshooting the data load process or correcting errors in the CSV files as necessary.

By following these steps, you can manually transfer data from Pivotal Tracker to Snowflake without the need for third-party connectors or integrations.