Im no expert, but as everyone else said...practice, practice, practice. May I suggest you increase the speed of the tanker to around 200K? The airplane should be a bit more agile at maneuvering. Second, have the airplane in trim before starting. Also, fly the TVV and not the boom. Keep your eyes on it, and use peripheral view to make adjustments... works for me at least, Im shure others have different techniques, just keep trying and use what ever works for you.
Hope this helps a little:
PS: Almost forgot...you will never get the correct thrust, so it will be a constant up and down of the throttles, just try to anticipate and make small corrections.