I still wear a leather jacket that was given by my piano teacher gave me when I was in high school.

I have only some patterns I usually wear, so I'm going to go through my closet and throw away my clothes they'at are too dirty.old.

In place of "old", we also say "ratty", "disheveled", or "worn out"

I still wear a leather jacket that was given to me by my piano teacher when I was in high school.

Not necessary, but clearer. Can also write. "I still wear a leather jacket that my piano gave me in high school."

I have only some patterns I usually wear, so I'm going to go through my closet and throw my clothes they'at are too dirty.

I still wear a leather jacket that was given to me by my piano teacher when I was in high school.

I have onlyonly have some patterns I usually wear, so I'm going to go through my closet and throw myout the clothes they'at are too dirty.

I still wear a leather jacket that was given to me by my piano teacher when I was in high school.

You can also consider shortening this to, "I still wear the leather jacket my piano teacher gave me in high school."

I have only someonly have a few patterns I usually wear, so I'm going to go through my closet and throw myout the clothes they'at are too dirty.

The correction above assumes that you're referring to patterns on clothes and not styles or outfits.

I haven't been that interested in fashion so far, but I think I should try to expandbroaden my fashion style.

This is good! For a more natural-sounding sentence, you can replace "expand" with "broaden." "Broaden" is the term conventionally used when talking about style.