Veneration of the Altar and the Book of the Gospels
273. According to traditional practice, the veneration of the altar and of the Book of the Gospels is done by means of a kiss. However, where a sign of this kind is not in harmony with the traditions or the culture of some region, it is for the Conference of Bishops to establish some other sign in its place, with the consent of the Apostolic See.
Bishops may determine some other sign, but the sign will need curial approval.
One of the more important distinctions for altar servers, not to mention other liturgical ministers:
Genuflections and Bows
274. A genuflection, made by bending the right knee to the ground, signifies adoration, and therefore it is reserved for the Most Blessed Sacrament, as well as for the Holy Cross from the solemn adoration during the liturgical celebration on Good Friday until the beginning of the Easter Vigil.
During Mass, three genuflections are made by the Priest Celebrant: namely, after the elevation of the host, after the elevation of the chalice, and before Communion. Certain specific features to be observed in a concelebrated Mass are noted in their proper place (cf. nos. 210-251).
If, however, the tabernacle with the Most Blessed Sacrament is situated in the sanctuary, the Priest, the Deacon, and the other ministers genuflect when they approach the altar and when they depart from it, but not during the celebration of Mass itself.
Otherwise, all who pass before the Most Blessed Sacrament genuflect, unless they are moving in procession.
Ministers carrying the processional cross or candles bow their heads instead of genuflecting.
This last point is important. We’ve already touched on the notion of the Book of the Gospels not “bowing” to the altar. I’ve trained servers to be careful about introducing the slightly comical sight of candles bowing, dripping, staining …
And as for bows, there are two distinct forms:
275. A bow signifies reverence and honor shown to the persons themselves or to the signs that represent them. There are two kinds of bow: a bow of the head and a bow of the body.
a) A bow of the head is made when the three Divine Persons are named together and at the names of Jesus, of the Blessed Virgin Mary, and of the Saint in whose honor Mass is being celebrated.
b) A bow of the body, that is to say, a profound bow, is made to the altar; during the prayers Munda cor meum (Cleanse my heart) and In spiritu humilitatis (With humble spirit); in the Creed at the words et incarnatus est (and by the Holy Spirit . . . and became man); in the Roman Canon at the Supplices te rogamus (In humble prayer we ask you, almighty God). The same kind of bow is made by the Deacon when he asks for a blessing before the proclamation of the Gospel. In addition, the Priest bows slightly as he pronounces the words of the Lord at the Consecration.
Are the particulars really important? I think it is important to cultivate a bodily awareness of reverence. Outside of the particulars, I’d say that excessive gestures tend to mark the person acting rather than the person honored. For instance, a priest who bows deeply over the altar during the institution narrative. Likewise a total lack of bodily gesture–the same result. Fly with the flock, and the individual bird goes unnoticed–only the destination.