Observation points is great for getting lore up, especially with a dumber race. When I last played a fire giant, I had it close to mastered when I hit hero, without ever spamming lore. However, if you're a fighter class with very little use for mana, the trick is to just pay attention to your mana and spam it when you see that you have a lot. When I've been really dilligent about that I've had it above 95 by level 40 with something as dumb as a storm giant.