I posted some floorboard questions a while back, and as I've now done
the job I thought I'd post what worked for me in laying my first
substantial floor, in case it's useful to anyone.

The job was to lay 30 sq m of pitch pine T&G floorboards, resawn from
old beams, onto joists at 400 centres. I had various questions over
how to lay and cramp, and what finish was likely to be successful.

The boards came in a variety of lengths, so a time-consuming part of
the job was selecting boards as I went, to minimise waste - it's quite
salutory to watch your 10 per cent margin piling up as a heap of
offcuts!

I left the boards indoors in the adjacent room for a month, to
acclimatise.

I was fixing with 50mm cut flooring brads, and a hammer. The boards
varied quite a lot in how hgard and resinous they were. Some were so
hard that the brads would bend as I drove them in, and I drilled pilot
holes. I also ended up drilling pilot holes at the ends of boards
where they met over joists, to avoid splitting. In th end I found it
quicker and easier to start every brad off by drilling 3mm or so into
the timber, and setting the brad in the hole.

I started out cramping up the boards one run at a time, but found this
a bit slow so went to two runs at a time. You could probably do three
but I was concerned to get them as tight as I could, and to check that
I wasn't wandering off straight by the marks I'd measured onto the
joists (which proved unnecessary). I cramped them with two of these
"decking instalation tools" from Toolstation:

http://tinyurl.com/yfnye2s

which at 9 quid a pop were a bargain. They're a cheap knockoff of
something American called a bowrench, and I found I could apply quite
enough pressure and they locked into position quite well. They do seem
designed to grip onto joists 2 inches wide, so I found a slip of wood
inserted alongside my 50mm helped make things tighter at points where
I was short of space to swing the handle.

I didn't make any serious attempt to sand the boards, as they were
newly-sawn and had laid pretty flat. I took a belt sander over, with
the grain, to take down any rough spots. My floor killed 9 belts.
Pitch pine doesn't sand easily! I've also blunted a saw.

For a finish I used Ronseal Mattcoat, which is a solvent-borne
polyeurathane. I listened to people's views on oils and waxes but
decided I didn't want the maintenance. I thinned the first of three
coats with white spirit, and applied the second two straight from the
tin, and am pleased to report that it seems to have penetrated,
covered and sealed quite well, even on the more resinous boards. Time
will tell, I suppose. It's a bedroom and there will be rugs, so it
doesn't have to endure hobnailed boots; though it feels pretty tough.
I denibbed with 180 grade paper before and after the final coat, and
the finished result is nice and smooth. I'm very pleased with it.

Cheers
Richard