How to bring the
DateTime format as DD-MMM-YYYY in SharePoint list NewForm.aspx?
For ease you should jump on making a Visual Web Part, hide the existing Web Part on NewForm.aspx and put in the Visual Web Part with all the code.. That is what I prefer! One thing you will loose the support of Ribbon, that's okay you can hide the ribbon and give your own buttons for Close and Save on the form!
In NewForm you cannot change the Date Format [only if you have InfoPath, which you will not because its in Standard/Enterprise edition not in SP Foundation]...
You can however hide the default NewForm's web part and add your Custom New List Item Form, and customize that; this will require playing with XSLT of the form which I personally don't like because its really difficult to set it correct!