God delights to use our hearts. There are four basic principles that God uses to guide us.
Principle One: Permission
God is a perfect gentleman. He waits until we give permission with our hearts for Him to do His work in our life. We, too, when helping others must recognize the importance of heart permission. So many times, more than I can count, I failed to get heart permission with someone I was trying to help and later found out that the person was not paying attention because their heart was not involved in the process.
Does God have permission to do whatever is necessary to prepare you for His coming Kingdom? God trusts His truth to your heart and He longs for full access to all of you. When He has your heart, He has you.
Wait for permission to minister to someone. They will let you know by a verbal or perhaps a nod of the head. You will become skilled in this area to be able to discern whether or not they are giving you and God permission to speak and minister to them.