Standard design principles say to install strip hardwood flooring parallel to the longest, unobstructed wall in the room. That gives you a good starting point and limits the amount of trimming and fitting you’ll have to do at the end of each run of flooring — but ultimately it’s your call.
Wood floors expand and contract with changes in humidity, so you’ll need to leave a ½-inch gap around the perimeter of the room. You’ll cover that gap with base shoe or new base molding.
Snap a chalk line about 1/2" away from the starter wall and set up a first row of flooring. You’ll install tongue-and-groove flooring with the tongue facing away from the wall.
Because of the shape of the flooring nailer, you won’t be able to use it close to the wall. You’ll have to face nail the first row or two. Predrill holes every 10 to 12 inches, and secure the starter row with 10d finish nails.
A flooring nailer is designed to drive nails or staples at the correct angle through the tongue side of the flooring and into the subfloor. You set each nail by striking a plunger on the nailer with a mallet. Set a nail or staple every 10 inches, and drive at least two nails into each individual piece of flooring.
Once you get the hang of it, using a floor nailer isn’t difficult. Just be sure to settle the tool firmly before each strike, and check the nail supply in the tool often.