After the proclamation of the Gospel, the homily (if one is to be given) is delivered. Very often, the celebrant will remove the maniple (the length of liturgical fabric tied to the wrist) and either lay it over the Missal or hand it to a server, who places it on the sedilia; this is, I suspect, a remnant of earlier days, when the homily was an extra-liturgical act. The best evidence that it is merely a remnant is the fact that it was also once customary to remove the chasuble (because the chasuble and maniple both are explicitly liturgical vestments), and this is virtually nowhere observed.
There isn’t much to say about homilies in the traditional form of the Mass, which, after all, come at the same time as those in the newer form, and which are still left largely up to the discretion of the celebrant. Of note, of course, is the fact that the older lectionary is theophanic in nature rather than didactic, so there traditionally never was an expectation that the priest would speak in order to expound on some meaning behind the readings of the day. The point of the readings wasn’t to communicate ideas to the people but to pray to God. That the priest wasn’t necessarily expected to expound on the readings was, to my mind, freeing: the celebrant needn’t lecture a somnolent congregation stealing micro-naps whenever he cast a glance at his notes about the ancient Judaic traditions surrounding the anointing of kings because, after all, we read 1 Kings today. He was free instead to exhort them to imitation of the life of some noble saint, or to explain a difficult teaching of the Church at a time when it had come under attack, or to chastise the congregation for some sin too many of them were encouraging, etc. There is some freedom with homilies in the new form, too, but a priest who seldom addresses the readings of the day can reasonably be accused of disobedience to the General Instructions of the Roman Missal, which dictate thus:
65. The Homily is part of the Liturgy and is highly recommended, for it is necessary for the nurturing of the Christian life. It should be an explanation of some aspect of the readings from Sacred Scripture or of another text from the Ordinary or the Proper of the Mass of the day and should take into account both the mystery being celebrated and the particular needs of the listeners.
This is obviously an artifact of the liturgical movement, more and more of whose energies were taken up in the former half of the 20th century with altering the liturgical actions to accommodate their own, inserted explanations of the liturgical actions, in the name of comprehensibility and participation. Telling, not showing, in other words, which rather deprives the action of some of its contemplative mystery.
One must also note that there is no expectation that a homily will be given at every single Mass in the traditional form. Very often, homilies were reserved for Sundays and feasts of major importance: at weekday low Masses, the homily was (and is) often glided over. This is fine by me: it’s not always appropriate to interrupt the liturgical action with lots of wordage, and the old Mass tends to run long, anyway (a daily low Mass celebrated at a moderate pace can take 45 minutes or more without a homily; a reformed daily Mass with a homily rarely exceeds 30 minutes).
Following the homily, the Credo is recited or sung (if at a Solemn or sung High Mass, in which case the celebrant first intones Credo in unum Deum before the choir takes over the rest). Here, as at the Gloria, the priest and servers make numerous additional gestures of reverence during the Credo that they do not make in the ordinary form of the Mass, most prominently genuflecting at the Incarnatus, rather than merely bowing (which many don’t do, anyway, in the reformed Mass, I suspect because it is a gesture alien to Western sensibilities and because self-conscious people don’t want to do something they can’t see other self-conscious people also doing). Note, too, that in the old form there is no option to substitute the Nicene Creed with the Apostle’s Creed. The Creed is said at far more traditional Latin Masses than reformed ones, owing to the former’s comparative abundance of major feasts which were demoted or altogether abolished in the new calendar.
In the traditional form, the Credo is followed immediately by a Dominus vobiscum leading straight into the Offertory; in the ordinary form, there are Prayers of the Faithful (also called General Intercessions or Bidding Prayers) jammed in between, in which a prayer intention is announced and a “For this, we pray to the Lord / Lord, hear our prayer” response is made. Some see the absence of bidding prayers in the old form as a defect, or as un-traditional (bidding prayers are found in certain Eastern liturgies and ancient-but-now-suppressed Western ones); I am perfectly okay with their absence, which, to my mind, break up the logical action of the transition of the Mass of the Catechumens to the Mass of the Faithful: first, we profess our faith (in the Credo); then, we enact it (in the consecration and offering of the sacrifice).