Golem can be a bit though indeed if you're not well funded or new to this game.
1 - Try to stack HP enough to survive at least 2 hits from his Power Attacks and Final Blow, wich damage increases as he loses HP, and bring lots of potions.
2 - If you can't face him directly, try to hit and run. Guard helps a lot here, if you do not have yet, I strongly suggest you to take and master it ASAP. Guard on, use an Uppercut on him and run. His Faint is dangerous, so you're gonna use the hit and run method to be as far as possible from him if Faint lands. When he stops running in your direction, go in and use another of your skills on him (if Uppercut is on cooldown). He has quite a lot of DP, so maybe your Tetra/Quad Punch won't do much damage if you have little AP and Uppercut would be your best bet.
3 - Don't go near him if he is surronded by Naranjos. Try to lure him away from his summons, or else they're gonna break your Guard with ease.
4 - Use a sprint. Buy a lvl 40 GB or 140 GB, or a Kitty Sprint if you can. Being able to move faster is gonna help a lot in the hit and run method, as well as making everything in this game faster than usual.
5 - Keep trying. Unless you're failing hard, don't be afraid to use some ressurrect scrolls on him, since you're probably not going to face anything so strong like him in quite a while.
EDIT: 6 - Boss characters in this game are good skill spammers, so a good trick to counter that is to keep pressing the HP potion button as soon as you see his casting glow on him. Don't wait to press if after your HP bar diminishes.
Hope it helps somehow.