The core gameplay structure in The Blood of Dawnwalker is divided between day and night. The official description presents different loops, abilities, mysteries and approaches for those parts of the experience.
During the day, Coen is human. At night, he is a vampire. The official material says the human form can use a sword and powerful magic, while the vampire form uses supernatural skills. It does not publish a complete list of abilities or tell players which form is always better.
Time also has a cost. The official site says that taking on a quest moves time forward, that Coen's family has limited time, and that he cannot help everyone. The safest confirmed advice is to read objectives carefully and record what changes after a quest. A complete optimal route remains unconfirmed.
Read the combat guide for the two forms, then use the walkthrough framework to track time and choices.