Screw placement to tighten and eliminate squeaks and popping
Gotta look at different ways to build step structure/risers. Get an idea of the different methods... 90 percent of the time the stringers are made from cutout 2X12's.  One on either side next to the edge and one in the middle. A stud finder is cheap and valuable.  Once you figure out the skeleton of your stair construction you will be able to do all of them. If you are covering your steps who cares about extra holes?  Shoot there are cool screws that pull the connecting wood towards the top wood...arghhh.  Can not believe I can't remember the name...we use 'Power Pro' .  Oh well, ask at your contractor supply store.  I would heartily recommend NOT using stick on carpeting for your treads!!