The first thing one should have in mind when doing the transition is the original character sheet for the character. The best approach for doing this is to account for every experience point spent in the character.
With that in mind, one creates a starting character based on the original character sheet for the character. After that, buy again everything that was bought with the previously accounted experience points. Most likely, due to incorporation of some charms into others and other changes in the charm trees. In case this happens, spend or throw away the remaining experience points, at storyteller's discretion.
Two abilities may pose a problem here: Brawl/War and Endurance/Integrity. To deduce the amount of points a character should have in War, check the Craft (War) ability. For integrity, there are two possible ways: one of them (the one I used when converting) is to buy as many points in Integrity as the character has dots in his Virtue Flaw's root Virtue. Another, more subjective way, is to consider the character's personality and then decide on what's the most appropriate rating for it.
Charm trees are by far the most troublesome portion of this convertion: this is where Exalted changed the most. A good point to start is Correlation. I do recommend, however, that you compare FirstEdition and SecondEdition versions of the equivalent charms to see if the requisites match, buying them if neccessary. For charms that don't have an equivalency, I suggest reading the FirstEdition version of them and adapting them using other charms of the same ability as a standard for comparison.
This is very crude, and subject to a lot of changes. Comments and suggestions are VERY welcome. -- Nabeshin