Gameplay gets much better in two, but the story takes a dive into the abyss. Get ready to read the wiki for hours if you didn't get it all in the end.
For one here is a few tips,
1.) Magic can be pretty OP at times. Things like thunder can hit multiple enemies at the same time, so later there will be times Thunder spells are like a screen nuke. Use Gravity on giant enemies to take huge chunks off their health. The bigger or heavier they are the more damage Gravity does. Also, aero is a defense boost spell which is really handy in the game.
2.) you don't have to do the cups in Olympus if you don't want too. They're great for extra goodies, but just finding the keyhole is good enough for story progression.
3.) In Deep Jungle, you'll be going up and down the level a lot. While there isn't a fast way to go up, there is a fast way to get to the camp from the tree house. There is a room that has a save point and a hole in the ground that you can jump in, which puts you in a sliding mini game like Tarzan does in the movie. At the end it puts you right at the camp.
4.) I wouldn't recommend giving Donald any Magic potions with auto refill after battles. He goes crazy with Magic and uses it up like 10 seconds into a battle, which means he will drain you of them.
5.) For Goofy, this one will fix tip 4. Later in the game Goofy gets a skill called MP gift, which lets him give up 1 MP to give a teammate 3 MP. Since Goofy does enough damage on his own, I always turned off his skills that use MP beside MP gift so he can focus on that. This makes it so you and Donald will have more than enough MP to destroy anything or use Aero and Cure all the time.
6.) Tinker Bell Summoning is broken. She essentially auto heals you until you die, then revives you and disappears. However, with skills like second chance and once more, which keeps you from being killed mid combo or one shotted, she practically stays around forever since she heals which keeps you only going back to 1hp instead of dying. Use her later to cheese boss battles you hate.
7.) make sure if you look up any guide you're reading the final mix version. Many things were changed from the original such as recipes for synergy items. They have added new heartless in that act like a mini game to get specific pieces for the recipes now.
Hope these helped in some way. Try not to worry too much about the combat and instead try to enjoy the Disney and Square collaboration. It's a pretty by the standards story and game that anyone can understand. It only starts to get deep and complex with Kingdom Hearts Chain of Memories, two, and beyond.
Edit: just realized this thread was bumped and didn't see. Well, if anyone who needs help with KH1 and is viewing this I hope my wall of text helps lol.
