When God wanted to communicate with Elijah in 1 Kings 19:11-13 He used a small still voice. People of modern times often forget that God can use that same voice to speak to us if we listen. The problem a lot of people face is that they are too busy tooting their own horn to hear the voice. Others must contend with thinking that the voice in their head is the voice of God. Sometimes, the voice in our heads is simply a voice in our heads. The Godly wisdom can help to discern between the two, but we must be willing to put our own intentions aside.
Once a person does something that takes away from the glory of God and puts the attention on themselves then it is not of God. People should be careful when they say the Spirit put this in my heart to tell you. The problem they may find would be that the spirit they are listening to is not the Spirit of God.