A few of the methods included in the spell leveling guide aren't efficient, or don't even mention some of the methods like the poison fountain for purity, and remedy.
Never turn the faces off, ever. Best spot in the game to level attack spells and weapons.
Use the faces in Center Tower 2 to level up ALL damaging spells, its simply the most efficient. Position in 1 spot and just keep casting, go refill, come back and repeat. Its simply the fastest method. The moles and golems take longer.
Purity and Remedy, you can level up in the poison fountain. Just click the fountain to get poisoned, then cast one of the above 2 spells. Remedy takes forever to level to rank 3. The slowest spell in the game to level up. Drinking the poison water ignores poison resist, so you get poisoned no matter what if you drink it, which allows you to cast and cure the effect without having to wait out the poison resist buff that eliminates poison by other means.
All of the buffing spells, just sit in front of the fountain and spam cast them.
For Earth Heal, I let the moles hit me then healed immediately. But the same thing can be done by letting the faces hit you with arrows.
Also, if you level up fists early on, they are actually really good, until you can get your hands on one of the special weapons. I can run around and punch stuff in the 1st area and have level 2 in fist relatively quickly. They are good because durability never goes down, and attacks are very fast. Undead, which are a good portion of the enemies you will be fighting early on are weak to fist damage, which is 100% blunt. After punching stuff for awhile, next thing you know fists are level 3 and you are doing beefy, quick hits without a weapon.
the one thing i have noticed is that the mole cave is ok to level up some spells but since the enemies here respawn randomly , i wouldnt recommend using this place to level up more advanced spells because its becomes a real pain trying to level them up. also, whenever you get the Lightning spell up to level 2 DO NOT try to level it up in the mole cave. since this is a very powerful spell you need to be outside and far away from your enemy cause if you're not, this spell can kill you instantly which means you need to be careful when trying to get this spell up to level 3.
Some of the offensive magic I like to level up in the Egg Field. The Bow Widda just outside the room with the savepoint and the transportation circle. He drops a scale quite frequently, and for every four scales you can get a fool fruit that increases your physical power by one. So kill him, transport back in and kill him again. I got enough scales to get 8 fruits in about 25 minutes this morning. Just got to make sure you don't kill yourself with your own magic.