This is done through normal story progression. Follow the purple indicator on the map and you'll eventually get this.
The only difficult part of Part 1, is chapter 4. It has an elongated fight sequence ending with what felt like a boss fight and an actual "boss fight" of the chapter. Neither will really challenge you if you understand the fighting system.
For the first fight, play VERY conservative early on. You have limited energy, and you might not have any health items (if you do, it should be easier). Use weapons as much as possible and try not to take any damage when possible. The "boss" is relatively easy, but again when the second part of his boss fight happens, fight him with weapons. I took a lot of hits at that point, but still won.
The best thing to do with the second boss fight in the club is to have a strong attack. If your opponent drinks and becomes on fire, back off and avoid him as best you can until he calms down. Then pound him before he takes another drink.