I've done the whole thing myself and my floors were dark brown, almost walnut, from neglect and abuse before I bought the house. Now they are a beautiful golden oak.
I learned a lot.
If you are only doing one section of the house make sure to seal it from the rest of the house. Tape over any air vents, erect a plastic wall at the border between work zone and non-work zone, and remove EVERYTHING from the part of the house that is getting sanded. You'll also need to get a smaller hand held belt sander for sanding the zone next to baseboards and thresholds.
Patience is your friend. The drum sander can be brutally unforgiving should your concentration lapse. It's nearly impossible to repair the divots that the sander can make if it rests in one spot. It doesn't really matter if you belt sand the edges first or last. I like last because then I can match the rest of the floor and there will be less to sand as well. The drum gets pretty close.
Start with 60 or 80 grit. Buy plenty of paper. The old finish will clog it quickly. After you have done the whole floor to your satisfaction in heavy grit progress to a finer grit and then finer again after you've done the whole floor at each grit. Smooth and tight is what you will be looking for on your floor's wood grain. Coarse grit will leave it fuzzy. You want smooth. Now do all the edges and spots that you'll use the belt sander for. Same with grit progression too. Be patient.
Vacuum. Vacuum. Vacuum. Vacuum. Vacuum. Vacuum. And then vacuum some more. You should be able to then take a damp cloth like a t shirt and wipe the whole floor. You are looking for minimal dust. Let the floor dry and wipe with the cleaned damp shirt again. Then do it again. Check all your cracks for dust residue and remove with a vacuum. Then wipe with the cleaned again shirt one more time. Be patient.
Breathing: wear a really good filter and clean or replace often. A hat is essential and goggles are great as well. Don't forget the patience.
I used a water based floor seal/finish and they are easy to apply...with patience...and being methodical. You'll need a foam applicator for the end of a broomstick (see Home Depot or Lowes). If you are going to use a stain and have really porous wood expect a drastic color change. Tighter wood like maple or oak wont change so much. Find an inconspicuous spot to do a test on first before starting the whole floor. For the stain a small t-shirt rag on the end of a sponge mop works well. Check it often for dust and dirt as you are staining. Get a paint pan for getting the stain onto the applicator. Be patient.
Once you have the whole floor stained. Let it dry...and be patient. This could take 1 or 2 days. Then wipe the whole floor with a clean t shirt rag. You don't want any dust. Oh, vacuum everything first. NO DUST.
Now you are ready to apply the finish. Think of this step as being the PATIENT methodical full coverage painter step. You want an even finish, no bubbles. You may see some, but watch them, and after 1/2 hour they should be gone. Don't do much until you've checked that they are disappearing. Slowly and with a slight overlap apply the finish all in the same direction over the WHOLE floor. Let dry - be patient. Check to make sure your applicator isn't getting dirty. Next day take some fine sand paper and knock down all the bumps in the finish over the whole floor. Get your clean damp t-shirt and wipe all dust off. Then do your next, second, layer of finish. Let dry. Sand then wipe clean again. Last day finally do your last, third, coat.
Congratulations! You're done. LET THE FLOOR DRY for 2 more days then move back in. Go to a fabric store and buy a foot or two of felt and apply it to the bottom of your furniture's feet with contact cement.
During the whole process - be patient!
I'll remain happily ignorant of floor refinishing, which helps you none at all!
