One of the things that always confused me was when to accept and when to reject the null hypothesis.
Since mnemonics are one of the best things ever, here you go:
Type ONE error:
You use a verb with ONE consonant => reJect => so you reJect Null hypothesis
Type TWO error:
You use a verb with TWO consonants => aCCept => so you aCCept Null hypothesis
& that's it! :)
-Murad