I will soon be ready to start laying hardwood in a bedroom - outlined below. The boards will run parallel to the walls with the doors (joists run perpendicular to those walls). The hallway outside the "door to hall" (and adjoining room) will have the same hardwood installed later this year. I feel I should start on either the wall with the bathroom door or at the door to the hallway. Should I start on the wall with the bathroom door and reverse direction to work the little square back to the hallway door? I know there is a chance that they aren't completely parallel - but the area with the door to the hall isn't lit very well, so an "adjustment" wouldn't be as noticeable. Should I rip a piece to use as a threshold there or just use the whole board (if I can) since more hardwood will be installed later?
Hardwood floors either have click-lock grooves or basic tongue and groove, but they all share that same basic idea. That means they can only be laid in one direction. The only place you can really start is going to be the top-left corner of your picture, and then move left to right and down towards the bottom.
If you start at the bottom, you can only move up, and that will cause you to have a transition strip of some sort in the doorway to the hall when you continue the flooring later.
When you stop in the doorway, rip a board to act as a "cap" for the edge of the last whole board. If you don't cap it off, the edge will get damaged because it's thinner because of the tongue and groove. When you're ready to continue, remove the ripped board to reveal a nice, protected groove to work with.
Is this "Hardwood" or laminate type engineered hardwood?
True hardwood, you start at the farthest corner and work your way out, either left->right or right->left.
Laminate woods, you would start any way you like, however, most people start in a corner and work their way out to the next room, this way you don't have as many transitions. Ideally, you want a transition from hall to bedroom, bedroom to bathroom. This is for aesthetic reasons, and to "form" a room.
If you plan to continue later and it is real hardwood, you would stop at the door and protect the last board, or not nail it down. This would then allow you to add on to the flooring to make it look like one solid floor surface, you may still want a threshold at the doors, again to "form" rooms.
Laminate flooring is generally a floating floor. Some people will nail it down in certain areas, edges and thresholds, etc. You need to read what the manufacturer suggests as the longest run without a joint. Some it is basically a 14x14 room that you can lay and then must install an expansion joint. Some newer floors allow almost an entire home without joints.
Many people will assume that walls aren't straight and either start in the middle or a few inches away from the wall. They'll put a backer board, and push up against that until the floor is complete, then cut a few boards to fit under the baseboards.
This is similar to how tile floors are laid out.
As to which direction, it probably doesn't matter all that much. Looking at my own room, the boards were laid perpendicular to the entrance door, but I don't see much particular advantage in that.
Thanks all for the info and suggestions. I am laying 3/4" T&G solid Hickory. I will start at the back/exterior wall and work my way toward the walls with the doors - measuring carefully to make sure I don't end up at the bathroom door with a sliver or some kind of weird situation at the hallway door. I am hoping the room is more square than it is flat (the subfloor has a few low spots I am working to fill in to bring it to tolerance). As long as it looks straight when I walk in the door from the hallway - all is good - fortunately I have a nice table saw in case I need to rip some boards at angles for the row up against the exterior wall. Thanks again!