I get what your problem is, I experience it often since I never feel my writing does my ideas justice xD
Erm, so I'll try to offer a bit of advice on it. It helps to know what your idea is and how you write because that's usually how I offer critique and help. Do you know how you're going to do it or the sort of 'style' (for lack of a better word) you want to write in?
If it's how bland it sounds then maybe try making your writing more 'flowery'? Try figuring out how you can change up the structure or the words you use to suit the mood and what not.
You can also try reading books of a similar genre and see how they write or what methods they use. How they would pick words that fit and how they very lengths of sentences for effects.
Sorry if you've heard this advice before but I'm just sort of going by what I usually see in people's works and what I think most people have trouble with which is -in most cases- word choices and overall structure. But then again this is Res where people only write because they want someone to read it and ignore their painfully poor grammar. Go figure.
Personally, I think what works best are more poetic works like Neil Gaiman and Jack London maybe because I'm a logophile but I adore those sort of works xD
Hope that helps even a slight bit. I don't mind reading and critiquing your stuff if you don't mind. :)