If it were me:
Sand thoroughly, moving progressively through the grades and vacuuming between them. For a very good finish wipe down with a damp towel to raise the grain and lift any stray fibres. Give one final, fine sand. Vacuum and use a tack cloth (or very very lightly damp J cloth) to remove any fine dust. Stain if required. Apply your chosen finish, working on 3-4 boards at a time. At this stage you should be in stockinged feet or have some of those elasticated things over your shoes (like shower caps?). De-nib between coats using wet and dry or fine steel wool. Allow to go off for a couple of days and don't allow heavy traffic for a week or more to give the finish a chance to harden. Use a good quality, long bristled brush (Signature Pro do a nice brush) and thin the first coat to help application. Take time with the sanding and vacuum cleaner- it'll pay off in a good finish.