That depends on how far you are, because of spoilers. [spoiler=Keeping plot stuff out of it, but it still may be wise to wait until you finish the game if you haven't already] Main thing is really to just not use the same resource for both food and levels, because it's pretty easy to get resource starved and that gets downright brutal the longer you go. The penalties get pretty steep no matter what you go for because... well, you're penalized for not investing in either, but there's never enough to avoid the penalties. A lesser note would be... Basically the entire battle system. It all looks brilliant on paper, but alternating between individual characters rather than factions punishes you for winning (and allows that one last enemy to steamroll through your weakened troops more often than not), the guard system heavily favors the enemies (especially late in the game), and tying health and damage to the same stat turns it into a game of rocket tag, again stacked in the enemies' favor once they start outnumbering you and bringing out their big units.