Quite right Rodan. Any trainee controller who tries to separate two aircraft with one or both on "own nav" and not a lot of spare space is likely to get a copy of the Air Pilot dropped on him/her from a great height.
'make your present heading a radar heading'
This usually means that whatever you are heading at the moment looks good to me for whatever devious purpose I have in mind, now stay on it until I tell you otherwise.
Don't forget, if you need to deviate from a radar heading for some reason (e.g. dirty big CB in your 12 o'clock), ASK.