There are various methods and techniques, to validate user input in python.

1. Data type validation: Check if the input matches the expected data type. For example, if you are expecting an integer, use the 'isdigit()' method or try converting the input to an integer using 'int()' and handle any exceptions that may occur.

2. Range or Length validation: Verify if the input falls within the desired range or length. For instance, if you are expecting a number between 1 and 100, use conditional statements like 'if input>= 1 and input <=100' to validate it.

3. Regular Expressions: Utilize regular expressions to validate input patterns. This is useful when expecting specific formats like email addresses or phone numbers. Use the 're' module in python to math the input against desired pattern.

4. Error Handling: Implement try-except blocks to catch any exceptions that may occur during input validation. This helps in handling unexpected input or errors gracefully and providing appropriate feedback to the user.

5. Sanitization: The input to prevent any potential secutiry vulnerabilities. This involves removing or escaping any special characters that could be used for malicious purposes.

By these techniques, ensure that the user input is validated, meets the requires criteria, and is safe for further processing in python application.