A: Firstly check the floor for nails and staples as machine hire companies make their money on burst sheets. Depending on how bumpy your floor is, start with a 24 or 36 grit paper, you should never go across the floor at a 90 degree angle. Anything 45 degrees or lower will flatten the floor for you, once it is flat "run" the floor with 36 grit. This means “with the grain” making sure you get all the "traverse" marks out. There are no real tips for the edges, just start with a 24 grit disk and finish with a 60 grit then re run the floors with an 80 or 120 grit sheet twice with either to get a good finish. Brush coat or roller on a varnish and make sure you buff in between coats and hopefully, if you’re competent enough, you should get the finish you desire.