I've played the game for a long time like 30 hours and I've gone through..

Buy the heal spell. Use it. Lots. It has a alignment modifier, so when you use it, the spell increases your "good" rating.

Defeating the game and making the right decision at the the end will make you 100% good, but something tells me you'll feel differently about this important choice at the end of the game once you figure out what it is. Until then, you can go the the Temple of Avo.

Each time you donate 1 gold, your good will go up 14 points. Keep doing that for a while, eventually donating 1 gold will start to give you only 13 points, but if you want to be 100% good, it's worth it. Also, when I beat the game, I made the wrong decision and I became extremely evil.

To get my alignment back up, I went to Cliffside path and kept kill and never ending army of undead for a straight 2 hours and it worked. Keep in mind that I was pretty evil at the time, so it took me a long time to get my halo back. It shouldn't take you long though.

First you buy a house. Then you upgrade it till you can hang a trophy on the wall. Then you break down the door. Then hang up the trophy and sell the house. Walk back in take down the trophy, then buy the house again, and it will cost less. Repeat untill you have around 100,000 gold.

(PS. This goes a lot faster if your trophy is worth more, like the bandit pass or the arena trophy) then go to the Temple of Avo, and donate it all. you get around 1000 good points for every 35,000 gold, give or take about a hundred.

Donate gold at the Temple of Avo or take a trip the the Cliffside Path near Lychfield Graveyard and kill lots of Undead.

If you're wearing clothing that gives negative alignment, you'll never be able to become 100% good on the status bar.