Discernment is a spiritual gift, along with many others described in 1 Corinthians 12. God provides every Christian with spiritual gifts; however, not everyone uses them. This is not something to be obtained by completing a checklist or improving your head knowledge; Discernment takes practice, and it takes development.
There are many sources of discernment and we'll talk about those as well as ask you: Where do you need more growth in your discernment on your spiritual walk?