Is donating blood for someone else wrong? Does it contradict with God's will?
Being a blood donor is a very Christian stance. This is an opportunity to help save someone's life and it does not at all impede on your own life. It does not contradict with God's will at all. It is actually a fulfillment of God's will. He gave His own life for us.
"Greater love has no one than this, than to lay down one’s life for his friends" (John 15:13).