The key to recognizing God’s voice is to have an intimate relationship with him. You’d recognize your spouse’s voice on the phone, right? But what about someone you’d only spoken to once twenty years ago? Not likely. It is of utmost importance that you spend time in worship and prayer EVERY DAY, not just once a week or, worse yet, Christmas and Easter. What if your spouse said he loved you, but only spent a couple hours with you twice a year? Not much of a relationship, is it?
Once you have a regular relationship with God that little voice in your head (your conscience, you think) will clearly give you the answers you seek. Don’t ask God for a sign. Asking for a sign is a huge mistake; it shows your unbelief. When the Pharisees asked Jesus for a sign he condemned them as “wicked and adulterous” so don’t be like them. Stick to reading the Scriptures and praying. A lot.