Bookwriting

I have several ideas that I think would make great foundations for writing books, but I just can't get it out on paper the way I want it. Very annoying. I envy people with the gift of writing. I am quite good at writing academic papers and similar stuff, but I am not as good when it comes to other types of texts. Do you ever feel like you have a great idea stuck in your head - but it won't come out properly?