I am a Level 4 Ingress player. I live in a rural area, so it has taken a lot of driving and some time to get to that level. I have been concentrating on finding unclaimed portals and filling them up with resonators, linking ad creating fields. This works, but it is a slow process. I have attacked a few enemy portals and gotten some AP for that, but you seem to get less AP for destroying fields than creating them.
I see several people who have made it to level 8. Is there a better strategy to get more AP and level up faster?