If your room is not square The best way to lay out the tiles is to use the most obvious wall in the room as your streight-edge guide. I believe the reason for starting in the middle is to divide the cut pieces you end up with at the corners in half. The big things to avoid are:

1. Having to cut very small pieces of tile.
2. Placing the angled tiles in the most obvious place.

You might for instance hide the angled pieces behind the toilet or under the kick area of the vanity.

Let me know how it goes because I have a bathroom tile job on my to do list and I don't thing there is a 90 degree angle anywhere to be found in my old house.

What method are you going to use to adhere the tile?

Kansaz; Sorry, I put reply in wrong spot. Anyway, I purchased a bag of white (the ceramic tiles are 8" white), #346 Sturdi Flex powder. But first I have to scrape the old Peel and Stick 12" tiles off the wood particle board. That takes quite a while to do. They've been on the floor for 20 years and are really stuck.

Sally,

Sometimes it helps to apply heat to the tile to help soften up the adhesive and save wear and tear on your hands. You can do this with a heat lamp or a hair dryer. Don't leave it on too long, just until it softens and the tile peels right up. It usually works, but not always.
You may also want to lay out the tiles on the floor beforehand to give yourself an idea of how it will eventually look before you do it for good.........

Sally, you might consider putting down some concrete board or 1/4" Luan plywood instead of removing the old tiles. Just a thought.

Kansaz nly thing, adding height to the floor may not work out because I am going to be taking out the fiberglass tub and also tiling under it, so part of the floor would be a smidge higher than under the tub, where there is no "Peel & Stick" tiles. Good suggestion, tho. Also, I will try the hair dryer treatment on the tiles. They're really stuck where there's been a lot of traffic for 20 years. I have to wear a mask. Someone said the tiles are asbestos and I don't know for sure. Is there a special tool to chop up the tiles? (OH! I'm replacing the fiberglass tub with an old fashioned footed tub; that's why it's coming out.) Guess that's about it.

Sally,

If it remains that difficult to remove the tiles, you may want to consider removing the whole floor and installing all new plywood. Sometimes what sounds the hardest is usually the easiest and fastest. Your time is money also. Rayl

I'm not usually one for doing things the quick or easy way unless I have to but I hate little nit-picky jobs. I have to say that rather than removing the old tiles or sub-floor. I would definitely get some new peel-&-sticks for spacers where the tub was. Then I'd lay down some concrete board and go to town with the new tiles. It really is nice to have under a ceramic tile floor.

Actually truth be known I'd probably do just what you are doing with the exception of adding the concrete board.

Kansaz, (Sally)

Your idea would work, however it causes added height to the floorline at the doorway entrance and with the water closet. Let's see what happens with the tile removal. I also think we should be in for a free dinner out of this............

Dr Home--You've got a deal! (but it's going to be 2003 by the time I get this one done.)
Thanks again for all the input. (H2O closet------is that the same as TOILET?) I'm new at this remodeling--you can tell!