Keep stocked with better healing items, keep a healer around, pass your turn onto your healer(s) if you need to heal quickly, buy armours when you can, keep adding skills via skill whispering. Get the jump on your enemy. Like, it's harder for me sometimes because my L-button is borked on my launch 3DS so I have to jam on it to do everything, but it's still doable. Enemies simply play on the same playing field as the player; this is not some sort of RPG where the enemies just stand around and do nothing because their AI is braindead, and you end up having the advantage and can get rid of them just by holding down A/X/Auto-Battle. Get a Napaea at the beginning of the game and you should be okay, especially if you transfer Dia over to your MC. Remember you can transfer the same skill that a demon has that your MC has as long as it can level up.
And because I'm going magic-focused with Flynn, I'm increasing his Mag/Ag/Luck statuses (luck will give me a higher likelihood for crits, for example) I'm not dumping much into strength because half the time I'm going to be casting magic in order to get an extra turn or to get the Smirk. Smirk allows you to do more damage and gives you a little stat boost for that battle, so carefully time it so that you get it at the beginning of your turn.
For most MCs in SMT, always go magic-focused. You aren't typically going to physically attack unless you're at the beginning of the game with less skills. So focus on Mag/Agil so you can hit enemies with their weakness faster. I like pouring things into luck because it'll affect phys crits, and the rate at which stat spells hit an enemy (so freezing an enemy, etc). Going for a Mag/Str build would mean that the MC wouldn't be likely to finish enemy groups off by himself. So going one extreme or the other (but you'll have an easier time with a Mag build) would be more beneficial to you. If you're going for a physical build, bear in mind that some enemies are resistant to physicals and that Pierce skills seem to only be available from DLC demons. You cannot learn passive skills.
The stats work like this (very briefly):
Strength: Self-explanatory. Boosts Gun skill damage. Boosts melee damage output.
Dexterity: Use this to max your gun damage output. Trust me.
Magic: Self-explanatory.
Agility: Affects turn-order and the likelihood of getting pre-emptive strikes.
Luck: Affects critical hits. People tend to underrate luck, but the luck stat is really one of my favourite types of stats next to Agility.
You can look at the SMT4 wiki for more info in terms of predicting damage output (Japanese Link): http://www34.atwiki.jp/megaten4/pages/273.html
Either way, welcome to SMT's Normal Mode. Hard mode is apparently unlocked when you beat the game or when.you answer the wrong thing and get the bad ending
But I heard that it takes a looooong time to restart after you die and that there's not soft-reset? That sucks.
Wow, that's a lot more than a expected, thanks. I'm dumping most of my points into Dx and Ag, so I guess it won't hurt to put more into Mg.
I'm getting the hang of things, I just have to figure out how to deal with Medusa.