Survive.
Also, your goals are specified in your blood. If you are a scion of Arturius, you might conquer and unify Britannia. As an Attilid you will devastate the world. etc.
It depends also on your religion. Some religions want to expand. Other want to unify. etc.
Your culture. As an amazigh, you will reconquer the lands that the arabs and the vandals took from your people.
Your state. the SPQR and Imperium Romanum will try to recover their glory past.
Actually, just read the description of your blood (if your character has no particular blood, your first quest might be to get one in your dynasty) and religion. It might give you some clues about what you will do next. You might also read the detailed timeline on the presentation page of the mod. It's a bit long but this mod is very immersive.