First I seek to get my heart into such a state that it has no will of its own in regard to the matter at hand. Ninety percent of the trouble with people generally is right here. Ninety percent of the difficulties are overcome when our hearts are ready to do the Lord’s will, whatever it may be. When you are truly in this state of totally seeking only God’s will, you are usually very close to the knowledge of what His will is. God, whatever You tell me to do, I’ll do it.
Having first done this, I do not leave the result to feelings or simple impression. If I did that, I would be susceptible to great delusions.
Next, I seek the will of the Spirit of God through reading the Bible. The Spirit and the Word must be combined. If I look to the Spirit alone without reading the Word, I lay myself open to great delusions. When the Holy Spirit guides us, He does it according to the Scriptures and never contrary to them. God never contradicts Himself.
Next, I take into account providential circumstances. As I pray, I look for doors that open and watch for doors that close. These often plainly indicate God’s will in connection with His Word and Spirit.
I then ask God in prayer to reveal His will to me correctly.
Thus through prayer, the study of the Word, and personal reflection, I come to a deliberate judgment according to the best of my ability and knowledge. If my mind is then at peace and continues so after three or more times of prayer, I proceed accordingly.
I have found this method is always effective for major as well as minor things.
Taken from Simple Trust Simple Prayers: Life-Changing Lessons from the Journals of George Mueller by Cindy Mallin, Appendix B, pp. 103-104.