My first time playing through I didnt do much of any "extra skilling up". I remember the fight with Algus at end of chapter 1, I was using one of those skeleton mobs in my main group. My whole group crystal'd cept ramza and the skeleton, who barely managed to finish off Algus. Then I got the new characters at start of chapter 2 and I was good to go again.

Then I had to completely trash the game cuz I got to Wiegraf, and did NOT have Auto Potion, or a Full battle Skill, or anything capable of letting me beat him. After beating my head on the wall against him for days straight, with my game saved in the castle where I couldnt go train, I just deleted the game and started over, and thats when I started building up JP/XP before I went to any hard battles lol