Regarding complete self-surrender, there is a nice description in the Eleventh Canto of Śrīmad-Bhāgavatam, Twenty-ninth Chapter, verse 34, where the Lord says, "A person who has completely surrendered unto Me and has completely given up all other activities is protected by Me personally, both in this life and in the next. In other words, I wish to help him become more and more advanced in spiritual life. Such a person is to be understood as having already achieved sārṣṭi (having equal opulences with the Supreme)." It is also confirmed in Bhagavad-gītā that as soon as a person surrenders unto the lotus feet of Kṛṣṇa, Kṛṣṇa takes charge of him and gives him a guarantee of protection from all sinful reactions. He also instructs from within, so that the devotee may very quickly make advancement toward spiritual perfection.
This self-surrender is called ātma-nivedana. According to different authorities, self is differently defined. Self is sometimes considered to refer to the spirit self, or soul, and self is sometimes considered to refer to the mind or to the body. Full self-surrender, therefore, means not only surrendering one's self as spirit soul, but also surrendering one's mind and body to the service of the Lord. Śrīla Bhaktivinoda Ṭhākura has sung a nice song in this connection. While offering himself as a fully surrendered soul, he said, "My mind, my household affairs, my body, whatever is in my possession, my dear Lord, I offer to You for Your service. Now You can do with them as You like. You are the supreme possessor of everything, so if You like You can kill me, or if You like You can give me protection. All authority belongs to You. I have nothing to claim as my own."
Śrī Yāmunācārya, in his prayers to the Lord, has expressed a similar idea in the following words: "My dear Lord, I may be living within some body as a human being or as a demigod, but whatever mode of life, I do not mind, because these bodies are simply by-products of the three modes of material nature, and I, who am in possession of these bodies, am surrendering myself unto You."
In the Hari-bhakti-viveka, there is a statement regarding how one can offer his body in self-surrender. There the devotee says, "My dear Lord, as a sold animal has no need to think about his maintenance and sustenance, so, because I have given up my body and soul unto You, I am no longer concerned with my maintenance and sustenance." In other words, one should not bother about his personal or family maintenance or sustenance. If one is actually surrendered in body and soul, he should always remember that his only concern is to be engaged in the service of the Lord.
Śrīla Rūpa Gosvāmī says that devotional service in friendship and devotional service in self-surrender are two difficult processes. Therefore such relationships with the Lord can very rarely be seen. Only for the advanced devotees are these two processes easily executed. The purport is that it is very rare to see surrender which is mixed with sincere ecstatic devotion. One must give himself completely to the will of the Lord.