When I first started on my '09 GS SE5 I would try to match the throttle to the next gear, and like usual I was not good at it. I just let the SE5 set the engine RPM when shifting up or down, it does a good job on it's own. If you shift at too low of an RPM the SE5 may not be able to match to correct RPM for the next gear causing it to miss the target speed and cause a hard shift.
I also agree with CyncySpyder that you should check the engine oil as this was the cause for some hard shifts for me once.