In my latest project I tackled the very old carpet on the stairs. Not too difficult to do a better job than what was already in place.
After removing the tired carpet came the unique chance to fix the squeaky noise coming from the staircase. I did this by screwing the threads and risers together, and adding a few brackets at the back.
The landing got the same treatment. It is very important to mind the pipes unless you want a water disaster one floor below.
After clearing the muck under the floiring, I found the source of the noise scaring the kids at night: a slightly loose pipe moving about when water is rushing through, banging against other pipes. Fixed with some underlay.
Before buying a new carpet for the stairs it is very important to accurately measure up the area to be carpeted, and draw it to proportion on a paper so as to understand how much carpet to order. It is necessary to build a 10cm allowance either side.