I was doing fine with Dragon Crystal on Game Gear (3DS version) till I ran into a big eye or something that insta killed me. I was like what the hell do I do to beat that enemy or do I run away.
I don't exactly remember what is good on what anymore but the game goes around using certain types of weapons to defeat certain types of enemies.
For example using the blue swords to defeat the cloud enemies, red swords to defeat slimes so they don't duplicate as much and so on.
There are enemies that rust your equipments, and if I recall it right the eyeball ones can rust your armor, which if you don't have a good spare or don't realise it you are quickly done for.
Those are problematic enemies as those snails that make you get hungry if you don't have a meal ring (or what it's called) and the cursed items can really ruin your playthrough if you don't have a scroll to fix it quick.
Running can be a good strategy earlier in the game as you get more bonus when you level up in the harder levels (for the same level).
There are also enemies that can make you level back down, so good luck with them too, as they can also ruin your game, lol.
But the biggest issue are the dragons, you probably didn't see one as they usually only appear in the last level (30) or rarely on the 29. Level 30 is filled with them and they are insane, I would recommend trying to run but they are programmed to follow you very well until they kill you, so if try to run you'll likely get ganged and hopeless. If you have anything less than the very best gear in the game you are likely to not be able to kill even one of them.
As long as you have the money you can get a bonus try but a lot of times your char will be ruined beyond repair so reseting might be the only option xP
The game is really unforgiving.