Pray. Ask God to inspire you. Many people can write lyrics, but few can write lyrics that are powerful, moving and anointed. Writing a worship song requires that you humble yourself before God while you bask in His majesty and glory. Only then will you be able to write a worship song that describes who He is and encourages others to join in His worship.
Write the melody. A worship song must be easy to sing. It should be written in a key that is not too high and not too low. Most people who worship in a church setting are not trained musicians. Your song should have a strong melody, not too many words, and simple phrasing. Everyone, young or old, male or female, should be able to sing your worship song easily.
Write the lyrics. Your lyrics should encourage people to worship God. Writing about personal experiences can be very powerful, but only if it ends with the attention being brought back to Jesus. A good worship song will touch people in a way that causes them to think about how awesome God is and, as a result, worship Him.
Add some scripture. Many worship songs are inspired by scripture. Using scripture when writing a worship song can help to encourage scripture memorization. Reading the Bible is a great way to get inspiration for your next worship song.
Write down your song. No matter how good your memory is most people will forget their lyrics if they are not written down. Also, inspiration for a worship song can come at the most unexpected time. Always keep a notepad with you so you can write down new ideas.
Record your song. Once you have your chord progression, melody, and lyrics, record your song to see how it flows. Playing back your worship song will allow you to identify any awkward phrasing or chord changes that might distract from the worship experience.