Beginning a story -
If you don't feel like writing at all, first try listening to some music while you write. The music doesn't have to be your favorite. And it shouldn't be loud, either. Just borrow a classical or new age CD from a friend or something and keep it loud in the background. If this doesn't work, try brainstorming by taking out a sheet of paper and just begin to write anything that comes to your mind, whether it's names or places or sentences and see where you go from there.

Important Grammar Usage -
1 - Try to avoid clichés like "hard as stone" and others. Make up your own. It's usually more fun anyway.
2 - Try to steer clear of run-on sentences and slang terms, unless you're doing it on purpose. It's hard to follow a storyline if your sentences are too long or if your audience doesn't understand slang terms.
3 - Don't overuse adjectives; provide them only when you feel they are necessary. But don't under use them either. You need a good amount of adjectives to portray a setting and it's characters.
4 - Keep your story believable!