Genesis 4:3-7 here we see two different sacrifices. Cain gave some of his crops & Abel gave the best portions of the firstborn lamb. They both gave an offering but only what Abel gave was received. This was because he gave his best to God. He gave God something that required him something. In this passage God rebukes Cain for being upset by God not receiving his worship. Not giving God your very best/flesh killing sacrifice can cause you to sin. This mean you have no control over your flesh. For worshippers your body is your offering whether it's your voice (psalmist), hands(minstrel) or entire body (dance). The type of offering/sacrifice is important. This means God wants you to study your gift (music and dance). Always look for ways to challenge yourself to get stronger in your gift with knowledge on the gift and building a relationship with the creator of the gift. The key for being successful as a worshipper is to deny yourself in order to get a better relationship with God. Time! God wants your time when your time is in high demand. God wants to know he is the reason and motive behind your drive to worship.
Don't give God worship that didn't cost you anything. Why? If you have to pay (time, talent, treasure, fast) for something you take care of it. If someone gives you something that didn't cost you anything you wouldn't treasure it as much as the item you paid for. Your heart is the altar your flesh is the sacrifice give it freely today.