How do you instruct and/or encourage members of the congregation to prepare for worship?
The best way is through consistent teaching and exhortation. This may be by way of sermons, brief illustrations shared by the pastor or worship leader during the service, Sunday School classes, small groups, etc.
Generally, people see worship as something only for Sunday morning. Until they understand that worship should be a part of everyday life, they will always struggle with the corporate worship experience.
Practically speaking, you can share Bible passages regarding praising and worshiping God all day long. Scriptures such as Psalm 34:1, Psalm 113:3 and Hebrews 13:15, all tell us that praise is to be an everyday part of life. It is not reserved for just Sunday morning. Offer thoughts on people in the Bible who actually praised God in their everyday existence. You could talk about David in Psalm 27:4-6 or Paul and Silas in jail (Acts 16:25ff).
Another idea is to relate ideas from our culture that might help people grasp this concept. “Would you go to meet with the president of the United States without making some preparation? How much more should we prepare to meet with the President of presidents, the King of kings and the Lord of lords?”
The important thing in all of this is to be consistent. Don’t have the attitude of, “We told them once, what’s their problem?” Other people are just like you. They have bad days. They get spiritual amnesia. They don’t consistently bolster their walk with the Lord. They forget. Because of this we all need regular reminders to keep pursuing the things of God. “But encourage one another daily…so that none of you may be hardened by sin’s deceitfulness” (Hebrews 3:13).
All of these ideas can help motivate people to understand that their own personal preparation will play a vital role in the corporate experience of worship.