I've done quite a few floors, you have to be patient and careful, keep it moving and lift before stopping, one slight hesitation and you will have a hollow that needs sanding out.
If you have that old gungy thick black varnish often used around the edge of the room then I'd recommend getting someone in, they will have the right paper that doesn't clog.
Go round knocking every nail/brad down below the surface, most papers rip easily on them.
You definitely need an edger (I tried it my hand - you'll die before the finish) and sometimes you need a hand scraper as well to get right into corners etc - I suggest something with a heavy blade like THIS
Sometimes its difficult to get a good surface match between the floor sanded parts and the edger parts because its cutting in a different direction - try doing different things with the edger to get best match and don't worry too much about the last inch at the wall.
On your first passes try and find the direction the floors sands best in for your finishing passes.
It is very very rewarding when finished but doesn't always feel like its going to be while you are doing it - choose a cool day, wear a face mask and seal the door with tape/cloth if you don't want a dusty house for the next 6 months.
If you want to maintain the colour of the wood on any gap repairs, use some of the sawdust mixed with clear varnish/shellac/resin.
The water based floor varnishes or paints are brilliant and easy to use, the varnishes are a hugely lot better wearing than the paints.
Ban stilettos from the room afterwards!!!