Hardwood floor refinishing is not something that you can take very lightly.  It is a large project and one that is going to take quite a bit of patience on your part if you are going to do it yourself.  Take the time to understand what is involved in the project before you jump in with both feet.

Make sure that you have all of your areas cleared out and at least one room that you can move everything to for storage.  This is going to ensure that the project does not get unnecessarily stalled at some point.  Nothing can be more frustrating that being ready to do another room and not being able to move forward because of this very reason.

Conduct a thorough investigation of the area to ensure that all nails or tacks are hammered down and flush with the flooring.  If not, they can ruin the sandpaper as you are stripping down the floors.  Now take the sander and move it across the floor going with the grain of the wood.  If you go against the grain, you can ruin the appearance.  Take your time and use straight lines.  A safety tip is to make sure that you have a safety mask on as dust is going to be flying all over the place and you do not want to breathe all of this in.

A common mistake during the sanding process is to let the machine rest in place.  You cannot do this as it will create an uneven area in the floor.  If the machine is on, it must be moving.  Once you have completed the entire floor, you should go over it again with a lighter gauge of sand paper than you used initially. 

When you have completed the entire floor, it is time to clean up the mess and get ready for staining.  You can use a common shop vac for the initial clean up of all the heavy dust.  From there, you can brush the floor, re-vacuum it and then use a tack rag to get the finer pieces.  It is very important that you get all of the dust up off of the floor so as not to mix with the finish.

Before you start to put down the finish, make sure that you have the area well ventilated.  Open any windows that you can and possibly turn on fans to make sure that the air is moving.  You should also continue to wear a safety mask to protect yourself.

It is best to apply the stain with a rag so that it is worked evenly into the wood.  Use long, even strokes to ensure that the stain has a good appearance.  If you want the floor to have a darker appearance, you can apply heavier amounts with a brush and then even it out with the rag.  Let the first coat dry and then repeat the process.

Once the stain has dried, you are ready for the final step, applying the polyurethane to the floor.  Stir the mix carefully.  Whatever you do, do not shake the can as you will create bubbles in the mix and they will show up on your floor.  Just slowly stir the mix to make sure that everything is blended in the can.  You can use a roller or brush to apply, but use the same event strokes you did when applying the stain.  When the first coat is dry, apply a second coat and allow that to settle for a couple of days before opening up area for heavy traffic again.