The first is hairstyle, you can refer to the recently popular "Beckham's hairstyle over the years". Cutting it short will make people mature.

The second is wearing, but this effect is not great.

The most important thing is to speak. Inner cultivation is the most important thing, which will make you feel calm and mature as soon as you come into contact with others.

However, you are only 17 years old. Is it necessary to change your nature for a woman who is no longer you? Just find a young girl who looks younger than you.