Need help, I'm still a beginner

I just played the game two days ago and I'm a katana user. Can someone help me to know what is the best stats for a beginner like me and how to get some good equipments for beginner and what skills should I upgrade first? Appreciate your help thx.

 

DEX for atk and accuracy.
VIT when you need more hp, AGI for aspd.
STR gives less atk than DEX but raises critical damage. (DEX is better against tough enemies, because you get more base atk)

the most important skill is Two-Handed, which boost your attack by 50% when a critical hit occurs. the sub weapon slot must be empty to use this skill, so no daggers.

MP Boost from survival skills is strongly recommended as well. it gives 300 maxMP at lv10.

that's what's recommended by the game, the rest is up to you.
you can use light or heavy armor, depending on your preferences.
regarding equipment, look for "unsheathe attack" stats.
normally, only the 1st attack, Shukuchi and certain skills are unsheathe attacks, but for katanas every auto-attack and almost all katana skills are unsheathe attacks.
each skill in the mononofu skill tree has a unique effect and distinct use from the others, you can't go wrong with learning all of them.