Is this a good strategy to attack DS questions?

It's a good idea to think about this, but you obviously don't want to spend too much time brainstorming - really, you should just always have those thoughts in the back of your head as you do a problem - as you're reading something, you should be thinking, "What does this really mean?"

You should also look at the information given in the question stem and see if you can rearrange or rephrase the information in a more useful way (before you even look at the answer choices). This exercise often then tells you what you need to know in order to solve the problem. For example, if they ask me something about (n^2 - n) where n is an integer, I can rearrange to n(n-1), which is two consecutive integers (n-1, n). That's a very useful piece of information.