You could start with the actuality of revelation - i.e. the point that revelation has in fact occurred. Within that, you could make your initialy point one about the objective actuality of revelation, in which case you'd be beginning with Jesus Christ as the incarnate Word, and the revelation of God in history. Or you could start with the subjective actuality of revelation, in which case you'd be talking about the preaching of the gospel and the illuminating work of the Holy Spirit. Both would make sensible starting points in some ways, the former because it lays the foundation for Christian doctrine, i.e. it is the most fundamental point; the latter because it is existentially and experientially the first point. There is also perhaps a third position relating to the actuality of revelation - you could start 'in the middle' as it were, with the doctrine of Scripture. That would make some sense as well - after all, that's how we know about Christ in the first place.
Alternatively, you could start with the possibility of revelation. In other words, you could begin by answering the question "how is it possible that God can be revealed to us?" That would cover the same ground, but from a slightly different angle. You could still start with the objective, i.e. Christ, or the subjective, i.e. illumination, or the mediating position, i.e. Scripture. But you'd be starting, not by describing revelation, but by analysing the conditions necessary for revelation to occur. Again, all would make sense. After all, ought we not to discuss how revelation can be, before we discuss what it is?
A third big set of starting points would be the necessity of revelation. This would mean starting with the question "why is revelation necessary?" You could talk about anthropological problems - the finitude of man in comparison with God, the sinfulness of man in the face of God. Or you could talk about theological problems - the wrath of God, the need for God to condescend in order to reveal himself. All would make sensible starting points in some ways, not least because it is not clear why we should worry about the doctrine of revelation until we've clarified these things.
All these things need to be said, but what you say first will set the tone for the presentation of the doctrine, and will affect the way you treat other issues later on.
I know where I'd start. How about you?