Let's take a look at the M's. These five are as you should expect... No big surprises
Write them out 10 times a day and soon you will get it. To aid memorization, make silly associations to go with them. You can use the above mnemonics or you can make your own!
マン ____________ This
ミート ____________ This means ____________
コーム_____________ This means ____________
メキシコ _____________ This means ______________
モーア _____________ This means ______________