1. Go for Manual Testing in the following cases: Unstable Software. To explore New Software. No Automation suite available. Adhoc testing (unplanned test cases). Not critical project & only one time testing & the effort required is less than the effort required for automation.
2. Go for Automation in the following cases: Stable Software. Any application with a High degree of risk associated with the failure is a good candidate for test automation. (Aircrafts, Patient monitor,) Testing needs to be repeated.
3. Advantages of Automation: Accelerate releases (reduces regression effort) With repeatable tests ensure consistency across multiple supported platforms Greater Application Coverage. Can test more often & more completely Convenient test reports for analysis