彼女は内気で、人前で話すのが苦手だ。
She is shy and not good at speaking in front of people.
I want to overcome my shy personality.
He has a shy personality and isn't good at speaking in front of people.
I joined the drama club to overcome my shyness.
He has a shy side, but once you get close to him he's a great talker.
She's shy, so she has a hard time talking to people she's just met.
内気 describes a reserved, introverted personality in general, whereas 照れ性 focuses specifically on becoming embarrassed or flustered in social moments.