When you get this Warning all you need to do is to initialize the variable when you create it.
Private myString As String = Nothing
My apologies for giving a misleading answer. I was completely confused with another issue I was experiencing where a Warning is issued saying that a variable is used before it was declared. Not sure why I thought it had anything to do with this question.
So for the down votes, thank you much appreciated however it would have been grand not to just down vote it but to also give a reason why and show the err in my way.