Yep, anything at all's okay. If you're talking about fiction or other creative writing, just do something -- anything. Some people only want to work on their grandest idea, their magnum opus, their masterpiece, and stick to that -- while other people find that way too daunting or disillusioning. The other approach is to set small, attainable goals -- write a description of a particular setting, or dialogue between two particular characters, or a small scene. Meet enough tiny goals and you'll have one big thing.
Beyond that, I think writing can only be a skill if it first becomes a habit. You gotta make yourself do it. If you can't write anything creative, write a letter to a friend or family member. Or a diary entry. Or a cover letter. There's always SOMETHING you can write, and every little thing helps you feel more comfortable with the process. Good luck!
