I have been in more depositions than I can count. Without fail, I encounter lawyers of all experience levels who ask bad questions. Specifically for this post, these bad questions are often too long, too complex, have double negatives, are compound, or are otherwise linguistically mangled making any answer ambiguous. How can you improve your questioning to avoid these problems?
To practice, read your own deposition transcripts. As you read your questions, think of ways you might have been able to ask that question more simply. Simple does not necessarily mean short. Sometimes it is necessary to have a lengthy predicate to the question, such as when walking a percipient witness through prior observations to lead to the next observation. It is like setting a table before a meal. However, a lengthy question need not be a complicated question.
Finally, in a deposition the most important thing is the record. But who cares if it takes you a few moments to compose the question? Who cares if you need to start and stop a time or two to compose the question? It is natural to experience frustration, perhaps even embarrassment, when stumbling over words in an effort to cogently phrase a question. Personally, I still stumble over words in depositions and need to re-phrase questions. It is merely a fact of being human. Instead, focus on your task. What matters is whether the question is correctly phrased to lead to the information that needs to be gathered.