Welcome to Gaia! ::

Well part of that is the fact that you are younger. Experience is the key to writing. What I can say is that you need to practice. Write for at least fifteen minutes every day and you'll see your writing improve.

Another thing is vocabulary. Read a lot as well, read books that have a wide range of vocab and words that you might have never heard of.

Also don't be self conscious about your work. Even if you think your writing sounds childish now it is still yours. When your writing don't think about how childish you may think it is, just write and enjoy what your doing. We don't always start out with expert writing skills. My writing was reaaaaally childish too when I was younger.

I hope that helped. Good luck. :3

Letting people read your work is crucial to the development of your writing skills. We won't bite and I'd be more than happy to read some of your work and critique it.

Another really important step to becoming a solid writer is reading. I can't stress this enough because by reading other people's works you can pick up on style, tone, voice, vocabulary and many other things that will influence your own writing. As an example I've read a lot of Cormac McCarthy and Stephen King novels and as a result a lot of my work is a little darker.