Correct, centering everything will not necessarily make the plane fly straight, but it's a good starting point to make sure we are all on the same page. I recently took up someones old cub they were using for training. They had just fixed it and everything was centered. It needed full left aileron trim to fly straight!

It's also a good idea to center the trims on the TX and mechanically readjust the surfaces to where they were. This way you can take full advantage of your trims if you ever need them again. (I knew I missed something)

I hope RC Ken has that link, I have yet to find an effective flowchart geared toward the beginning pilot. I have a flow chart for this, but it's geared toward advanced aerobatic pilots and requires the pilot to put the airplane in situations uncomfortable to the beginner.