Pay firm attention to the non-commercial signage in the sparsely populated zones. They provide handy tips on how to avoid going straight to hell when you die or other factoids about babies. Some provide back-up illustrations, but most have hand-written lettering and can be boring visually so you might miss them.
Really, you should just ignore the green highway signs and read the others since eternity in hellfire prob sucks way more than missing a stupid exit.