This will come naturally over time, but to speed it up you should focus exclusively on the following activities:
1) main story quests,
2) world events, and
3) killing ancient order targets and zealots
When playing I would usually go up 40-50% of a level each time I completed a main quest, and ~20-25% of a level every time I completed a mystery. I personally tried doing mysteries whenever I found them. In addition, some mysteries are incredibly short, such as paying a bard to write a song about you. Above all, have fun!