I'm assuming you're starting with a fresh CAST, right? I can tell you how I got started and what was the most efficient way for me to progress: Start with running Unsafe Passage and unlock Fight for Food. Keep doing Fight for Food until hitting character level 10 or run it until you hit Ranger 10, that way you can upgrade to ForteGunner. You should be able to speedrun Fight for Food quickly so it shouldn't take long. Pick up everything, and sell what you don't need. Use the money to buy the PAs you plan on leveling for GunMaster. Go and do Mad Creatures to get to Raffon Field Base. Now, this is where you can easily level up your PAs while leveling up your character and job. Plains Overlord is great because you can go into these safe spots where no mob can reach you and happily shoot them down until dead, then move on. I use the rifles and twin handguns while making my way to De Ragan, and then use shotguns on him so it won't take too long to kill him. Shotguns level the fastest of any range weapon, so you don't have to worry about them being under leveled for the most part. For lasers, Sleeping Warriors. No safe spots to hide in, but most of the mobs are small and weak, so they shouldn't do too much harm to you. They bunch up as they come towards you, so get into position where you can hit multiple targets easily. Use shotguns on Polavahras and Svaltus'. That's basically it. You'll level with your PAs, while saving up money to buy new gear like line shields and weapons, but this is if you plan on hard grinding your PAs right from jump street, which is tedious as heck. The only other advice I can give is play the game normally.