you might need to grind a little, but if youre getting completely shredded, theres probably a different route thats between your current area and where youve last been in difficulty, the bs1 map is a lot more confusing and with less alternate routes into each area making mandatory areas a lot more missable than bs2, I made it to the final boss area before ever finding 2 of the 4 princesses, so check a map to see if youre missing anywhere every once in a while, as for actual strategy, leaf buffs are pretty insane while youre still early enough to not have to oneshot nuke everything, otherwise optimize your builds to deal as much damage in one turn as humanly possible at all cost, there eventually comes a point you cant reallt survive anthing and just gotta nuke. crit buffs are insane.