Some people who study Japanese have same question about difference

of シ（shi） and ツ（tsu）. So I write here the advice about it. Before writing Katakana, please try to write big し（shi）and つ（tsu）in hiragana. After that, please try to write katakana on it. I mean the 3 lines of シ（shi）start from same virtical line. The start points of 3 lines are from same virtical lines of し. Then 3 lines of ツ（tsu）start from same horizontal line. The start points of 3 lines are from same horizontal line of つ. I'm sorry for my terrible English. I hope this advice helps your study.