Agreed, the game lacks some ways to catch up as a new player. If you can't find an area that you can destroy as a level 1, you will level extremely slow. Let's see, you need 10000AP for the first level up & 30000AP for the second level up. As level 1 you can kill a level 3 portal tops. In case flipping portals is no option due to higher level players in your area, all you can do for points is:
- Hack enemy portals for 100AP
- Recharge friendly portals for 10AP each (portal resonator XM decays by around 10% each day, so you can usually recharge three times per day)
As you can see, being outleveled is not even as worse as having no opponents at all. Having 5 hostile portals in your range seems likely for most areas, so you can do easy 5x4x100=2000XM just by hacking them till burnout (after 4 consecutive hacks) each day. This means 5 days for level 2 and another 15 days for level 3.
After that, the game mostly opens up, you can attack most portals with level 3 if you have enough ammunition. You will most likely don't have level 7-8 portals in your area for long, as those are field cornerstones that scream for attention and lead people to drive out and nuke them to pieces usually. Once level 3, you should focus your effort on farming (this is the most important part of the whole game, get a friendly farm started, in the best case, multiple portals that you can cycle through within 5 minutes), and blowing those portals down that contribute to an enemy field. Just blow the field up, grab the portal and get going back to farming mode. It is a juicy spot for the enemy, as they still are only a single portal away from completing a field (again), so they will redeploy once more. Nuke the portal down until they don't feed you AP anymore, then take over the whole field.
By now, you are already knee deep in, you will figure out the rest on your own