I've been playing this a while, let me give some tips here.
- Cheat engine works well for items and gold, everything is 4 bytes. Cheat engine works best with larger values, save up enough so that you can buy/sell/change the value at least three times if you have low values (< 10 or so), high values can be done as easily as one buy/sell/change. Just make sure you change the value ASAP, the value doesn't stick around forever.
- If you want to go for the good karma route, 1 key is for information on NPCs, and its karma free as far as I can tell. You can also use the kinder/informational orders without fear, there's no indication that it hurts karma. (hug me, hold my hand, tell me about yourself, etc.) Avoid anything sexual. Don't use 2 except on the fairy who gives you see invis item, and always help/spare everyone, except for the blatantly evil dude who splits your party. Don't pray at any dark/evil statues either. The rest is fairly obvious. When in doubt, use common sense and see if your party members complain.
- You can buy a number of materials and some REALLY good equipment, check the left side (book I think) at home base. You can get some stuff at the explorers guild you can access at the shining point at home base as well, and at level 3 of Pandemonium you can buy from the Demon Town. These are all available shortly after starting the game. (You need to rush through to get to the Demon Town safely.)
- Night time gives different materials when harvesting.
- The happy fairy takes damage from a non-lethal attack Irito learns.
- Any equipment or skill with a star by it means its maxed at the moment. You can max stuff by using it for skills, wearing it and winning battles for equipment, and equipping teaching weapons followed by winning battles for skills.
- The girls like you more as you win battles with them, you'll see hearts. You should try and learn the bonding skill ASAP so they gain skills/levels as they do so. Get the archdemon crystal things by getting 50 acclimation and defeating boss monsters on 1F, cheat them so you have more, then buy all the passive skills from the vendor in Demon Town on 3F.