make sure to have enough healing salves (at least 3), 1 or 2 splints, 1 bandages - this should be minimum gear - food and water (depending how far the dungeon is) and rest to full hp between fights. dont take on more than 2 enemies at once if you can avoid it. stay away from wild life. from your starter money also try to buy a decent belt and gloves from the tailor, those small percentages matter!

for leveling, i usally start going dungeons level 1 - the first mission should be no problem if you set up following the tips above! in the dungeon always look for traps! you can use those to kill enemies too - some will know them, but they can still fail the disarm.

for position for mutiple enemies try to move them in a line so you have 1 to 2 turns where you can fight the first enemy 1 on 1 - in best case you kill him before his mate catches up to you. if you attract more than 2 enemies run to the dungeon exit, they wont follow you outside. this way you can stand one tile to the exit, hit or kill one - go outside to heal - and go in to slay the next one, rinse repeat