Re: refinishing pine floors
Use a Random Orbital sander with 120 grit to clean up the low spots to prepare it for the finish. Vacuum several times to remove as much dust as possible. Damp wipe down clear water to get a feel for what the finished look will be.
I would use oil base poly, my preferred brand is OldMasters because of its excellent self leveling characteristics and hard finish.
I would not stain, pine will darken naturally in time. Wipe down with a tack cloth to remove remaining dust. First coat, thin poly 25% and apply as a rubbed on coat that will help push the poly down into the grain of the wood for more durability. Then apply 3 coats of brush on. For a clearer finish apply 2 coats of high gloss followed by one coat of semi gloss. Semi gloss will look pretty mush like satin but is a little harder.
Be sure you live your life, because you are a long time dead.-Scottish Proverb