What I have learned from my past experience making outline is the best practice. I endorse all the suggestions of waseem gurmani.
In nutshell, it saves your time, gives a well thought path to follow without stopping at any time during your exam time, it keeps you balanced, helps you to manage time, above all its pressurizes you to produce more and more in a clear cut way which is relevant.

When you are not sure about the relevance and correctness of your outline then write down outline on any rough page in the paper. That will surely help you while answering the question. For the sake of hiding your weakness don't present that outline in the answer just take it as your groundwork.

I have been in habit of writing down the key points / outlines on the question paper infront of the relevant question as soon as I read the question. That helps me a lot to write logically and manage the time. Even that helps me in deciding the sequence of questions which should be attempted first and which should be left for last hour.