The stroke direction and angles are important factors in distinguishing katakana symbols.

 

-so- katakana so -shi- katakana nn

The second strokes of ソ (-so-) and ン (-nn-) are written in the opposite directions as shown on the left. To emphasize the direction of this stroke, we often put a small hook at its beginning. The following animation may help you associate katakana ソン with hiragana そん.

 

morphing-so vs. morphing nn
   
-tsu- katakana tsu -shi- katakana shi

Similarly, the last strokes of ツ (-tsu-) and シ (-shi-) are written in the opposite directions as shown on the left. To emphasize the direction of the last stroke, we often put a small hook at its beginning. The following animation may help you associate katakana ツシ with hiragana つし.

 

morphing tsu vs. morphing shi
   
katakana so katakana ri
The angle of strokes is also an important factor in distinguishing symbols like ソ (-so-) and リ (-ri-) . The two strokes in ソ are slanted inwardly while the strokes in リ are parallel to one another (initially).
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