I'm a member of some SE sites, like SO and CSTheory. In those sites I'm an active member, I'm reading Q&A and also answering some questions or asking questions, but I think my writing is poor.
I like to write letters without thinking about grammar (like a child), but I think I'm a bad writer, because too many times my questions and answers are being edited. In fact, most of my problems are in my questions. I don't know how to ask good questions, which means I can't express my problem well (but my answers are not too bad).
I want to improve my writing, specifically when I want to ask long questions relating to my field (Computer Science). What's a good practice for this?