Be More Specific!

Hey there Mibbians :D

I've been having a lot of troubles with my writing lately. I feel like I'm fine when it comes to writing, but my peers find it to be (gasp) not specific enough. Today I let a good friend of mine read a rough draft of what might be my next story. (I write about whatever comes to my head.) And she implied that my when I'm describing something I could be a little better at describing it. How could I better my writing when it comes to specifics without just writing a whole page about a single character? Do you have problems with specifics?

I'm also looking into writing a fanfiction. (I'm debating on it.) I haven't been really into fanfiction because almost all of the ones I've read are about bands and girls fantasizing about sleeping with them. Hopefully if I do decide to do it, it turns out well. I've never written a fanfiction before. D:

P.S. If there is any good fanfiction out there would you mind telling me what they are? I'm curious as to what other people write about when it comes to this stuff.