I've used the I Ching for many years and I love it. The way to ask your question is along the lines of: What will happen if I do X? After studying your response to that, you can as the opposite question: What will be the outcome if I don't do X? When you have more than 1 changing line, then then the highest number carries more weight than the other changing lines. Example: changing lines are 2 & 5. Line 5 carries more weight regarding your question. When you use your changing lines to progress to the follow up hexagram, that hexagram will tell you what will happen if you follow the advice of the 1st hexagram.
I hope this helps for anyone who is asking Yes/No type quetions, or looking for more direct answers to their questions. Also, there is a great book for interpreting your hexagrams (in my humble opinion) and it gives a good history of the I Ching. I can't remember for sure, but this might be the book that taught me how to phrase my questions. It's "The I Ching Workbook" by R. L. Wing.