level lasers damage and width 1st, followed by mana points and mana recovery
for spells wait until you unlock lava slugs and put everything into that. if you find yourself almost dead all the time you could wait for the next spell bat bullets. they steal health, but do far less damage.
once you get every bonus stat and max lava slugs go for the 2nd 500 point outfit shown in image

once you hit part 2 all character upgrades are now gone. soo your gonna want a maxed out spells