It has to be a way of life. IMO, worshiping in Spirit and truth means to constantly be laying your life down on the altar and living with an attitude of thankfulness. You have to show your worship in your actions consistently and desire God's pleasure and His will to be achieved in your life; otherwise, when you show up on Sunday and sing some songs, then it is not in truth, much less in Spirit, it is a religious lie.
Once you determine to live in worship mode, it spills over into the expressions that are made through music. For example, I dance a lot in worship, and I love to sing to God, but it's not because I enjoy dancing and singing. It is because He's filled me with new life and joy and passion so that I have to express it. That is where the psalms and spiritual songs Paul spoke of will come from. As for worshiping in Spirit, I think it is a submission to the Holy Spirit and having your ears tuned to what He is doing and desiring in your life and in your times devoted solely to God.
But I think you have to just search it out for yourself--Psalms and Song of Solomon are two great places to learn about worship and intimacy with God, as well as 1 and 2 Samuel--all the accounts of David's life reveal so much about Scripturally sound worship.