we japanese have a simple way to remember it
' nishi muku samurai ' (' a samurai facing to the west)
ni means two
shi means four
mu means six
ku means nine
thus these mean february, april, june and september

' samurai ' part is a bit hard to explain...
there is the word ' bushi ' which is synonymous with samurai
and the kanji for ' shi ' in the word ' bushi ' looks like ' ten plus one '
therefore it means november