Blog help!

Hello everyone!
I'll make this as simple as possible :-)

I'm 17 and have always had a love for writing. I really do want to become a blogger and social media influencer but don't know where to start!

I know that research is key! I am researching and have come up with a few blog topics such as teen life, lifestyle, beauty etc but all of that is already out there!

I want to talk about something I enjoy, I really do want to help people out with this blog. I know being a teen can be very stressful and just as YouTube is very popular with teens I want to reach out to a large audience mainly teens and find a way to help them!

Have any of you started successful blogs around teen life?
I really want to start one but don't know what type of posts to put under the teen life topic... I also aim to make revision a topic within the blog for both GCSE's & A levels.
What other topics could I talk about? I have a few: teen life, beauty, fashion etc...
What other topics?

I am really passionate about this and want to raise awareness of things such as bullying and culture in a teens life.

Any advice is appreciated :-)
Thank You