In these games the main focus are the consumable items, mostly used by the alchemists since they tend to have a bonus when using those.
Buffs, debuffs, damage of the right element, all of that can come from items.

For your equipment, make it with as effects as high as possible and quality as high as possible.
When that isn't enough, get into traits as well.
There is no specific stat that is better than others in all cases.
Since your non-alchemists are going to use their attacks and skills more often than your alchemists, anything that increases the potency of those attacks is nice obviously but in most cases your elemental bombs are going to matter a lot more anyway.

Oh, and buffs and debuffs stack, so put them on all of your consumable items when possible (through traits for example), it also helps when trying to burst the shield of bosses.

Maybe a given but taking the time to remind that quality is an important stat, since it affects;
• Equipment: The 'total quality' stat that raises all your stats.
• Consumables: Healing/Damage power.
• Seeds: The quality of materials you'll get (Which is mainly how you'll be able to get most materials at better quality).

I recommend combining traits to get to the all stat increase traits, and stacking those on every piece of equipment you have, whether it be accessories, weapons, or armor. Quality is important for equipment, but you want to mostly prioritize effects and traits for equips. Your attack, defense, and speed scale scale 1:1 with your equip quality stat, but your HP and MP do not.

Your main form of attacking will likely be bombs, prioritizing effects and quality, then traits. 999 quality is somewhere in the ballpark of 4x damage compared to 50 quality iirc.

Stacking all stat traits and keeping on top of your bombs as much as possible, and keeping buffs/debuffs handy will ensure you absolutely shred everything. By the 3rd major boss I was only taking 1-2 damage from attacks using buffs/debuffs, very useful stuff.

Reminder that trait combinations are how you start getting access to the busted stuff, and you can pretty quickly work your way up the trait list.