My first solo backpack was Horseshoe Meadow to Whitney Portal. I had a few seasons of backpacking experience. It was a wonderful experience.
There is enough information out there today that your trip should be anything but unnerving, if you go out a few times locally with your gear and get use to it and learn what does and does not work for you.
Just remember, there is nothing special about Mt. Whitney it is just a normal backpacking trip. You prepare for it just like any trip to the Sierra. No extra this and that.
