1)    When bowing down in the Amidah, he should bow down quickly and in one go, and when straightening up afterwards, he should straighten himself slowly, starting with the head and afterwards with the rest of the body. He should do it in this way so that it does not look like the bowing down is a burden. (Shulchan Aruch and Mishne Berurah 113)

2)    When saying the word “Baruch” he should bend at the knees, and when saying “Attah” he should bow all of his body, and when saying “Hashem” he should straighten himself, as it says “Hashem zokeif kefufim”. During the blessing of Modim he should bow his head and all of his body in one go, and he should remain like this until he says the word “Hashem”, and then he should straighten himself. (ibid)