This is from commentary of Baladeva Vidyabhusana, Vishwanath Chakravarty Thakur on Bhagavad Gita 18.66
sarva-dharman parityajya
mam ekam saranam vraja
aham tvam sarva-papebhyo
moksayisyami ma sucah
As per Vayu Purana,
anukulyasya sankalpah pratikulyasya varjanam raksisyatiti visvaso
goptrtve varanam tatha nihksepanam akarpanyam sad-vidha saranagatih
Surrender has six factors: accepting what is favorable, rejecting what
is unfavorable, having faith that the Lord will protect one, accepting
dependence on the Lord, placing oneself fully to the Lord, and
meekness.
Below are the explanations given by different acharyas:
As per Baladeva Vidyabhusana:
Actions pleasing to the Lord that are prescribed by the scriptures are
called änukülya or favorable. Opposite actions, displeasing to the
Lord, not prescribed by the scriptures, are called prätikülya or
unfavorable. Ätma nikñepa means “to place responsibility for ones
maintenance in the object of surrender, the Lord.” Kärpaëya means “not
bold.” Sometimes the line reads nikñepaëam akärpaëyam. In that case,
akärpaëya means “not showing ones miserable position to others.” The
rest is clear.
As per Vishwanath Chakravarty Thakur
Anukulya means conduct pleasing to the Lord and according to the
scriptures. Pratikulya means the opposite. Goptrtva means to think of
the Lord and no one else as ones protector. One should have faith
(visvasah) that in times when ones own existence is threatened, the
Lord will give protection, as in the case of Gajendra or Draupadi.
Nihksepanam means employment of ones gross and subtle bodies for
Krishna’s service. Akarpanya means that one should not make a
show of ones own humility.
Below two are from footnotes in the book I referred:
As per Jiva Goswami
Jiva Goswami explains in Bhakti Sandarbha 236 that goptåtve varanam,
accepting the Lord as master, is the very definition of surrender, and
is therefore the main item. All other five items are its assistants.
Ätmanikñepa means to have no independence from the Lord. “Whatever he
orders, I do.” Kärpaëya means complete humility. “No one is more
merciful than you, and no one is more fallen than I.”
As per Vedanata Desikan
Vedänta Desikan takes ätma nikñepa, placing responsibility for ones
maintenace in the Lord , as the main item. Goptåtve varaëam is praying
for protection, which is similar to rakñayiñyatéte viçvasaù, faith
that the Lord will protect one. Kärpaëya is feeling hopeless and
incapable, and therefore with humility surrendering to the Lord.