"Jump to 30 nebula locations before sector 8."
While this may seem like a tricky feat, it's quite easy. Delaying the Rebel Fleet and Nebulas will help considerably in exploring as much of each sector as possible. Once you've jumped 30 times before The Final Battle, you'll nab this achievement.
Another option, if you managed to pick up another laser weapon or flak and have decent shields and engines for your current progress, is to repeatedly farm elite rebel fighters after they catch up with you in a nebula sector. The plasma storms will greatly limit what weapons they can bare against you at once and there is no ASB. Just be careful to escape if your hull is too far damaged from stray hits.