if ur a mnemonics person, try
Memorising the Hiragana and Katakana - Contents
but i find mnemonics actually make my life harder sometimes.
most importantly, write all freakin' 46 of them like at least 5 times everyday or at least 20 times each week. Don't forget to try reading to improve character recognition which also improves how you write. i notice that the more i write, the better my handwriting (meaning that it doesn't look all americanized)