こんにちは！Ok, so no matter how skilled you are in にほんご, カタカナ is still pretty stressful and difficult! Especially since the words are not direct translations from English, as サトせんせい said, "カタカナはえいごじゃあありません！” "KATAKANA IS NOT ENGLISH!" So, there are a couple of things you can do to help you memorize カタカナbetter!
いち： パートナーとれんしゅうして！Practice with a partner! For example, エンシソさん (Enciso-san) and I had a dictation study/party session! It can be really really fun and you learn faster because it is just like the quizzes but outside of class! The more we practiced, the more we laughed at "プープール" ("purple" which turned out to be パープル not the hilarious プープール), and the faster we got at reading and writing!
に： よんで！よんで！よんで！かいて！かいて！かいて！Read and write! You know the sheet サトせんせい gave us in class about ファイブガイズ （Five Guys)? That is actually REALLY helpful! It tests and builds on your ability to read faster and fluently!
さん： WATCH ANIME! Ok, not just anime, but watch Japanese cartoons, or anime, or J-Dramas (shout out to Enciso-san), or listen to Japanese music! You start to pick up little words here and there that they borrow. FOR EXAMPLE, I just watched an episode of an anime and the guy kept saying "ボイ” as in "Boy" and わかりました I understood!
Soooooo, I HOPE this インフォメーション has been helpful...if you still can't read that, it seems that you should practice more...HAHAHAHAHAHA, I'm kidding, I am still learning at a slow pace and I follow my own advice to the utmost. For example, I am going to go do the Japanese homework due tomorrow!!!