What does it mean to serve God?

You can serve God in a variety of ways. Serving humanity and all creations earnestly is serving God.One who loves humans and all creations earnestly with sympathy loves and serves God.

Praying is a ritual in ones conviction that he/she is serving God. Charity is a conviction that one believes that he/she is serving God.

Every religion sets doctrines to serve God.Followers of the Jewish,Christian and Islamic faith believe doing what He has asked you to do. viz..Following His commandments.

Exodus XX tells us what the commandments are. We should strive to be saved and surrender our heart to God. Cry out to Him. God is not pleased with people who are lukewarm in their service to Him and turn around to sin in vices of the world in adultery,greed,hate,envy and pagan rituals of drinking, partying,etc.

Romans XII states that we shouldn't be conformed to the world but transformed by the renewing of you'r mind that ye may prove what is edifying and pleasing unto Christ.