The second furring strip should be positioned so the distance between the center of the strip and the wall is the width of your border tile.
It is critical that the remaining furring strips be exactly parallel to this strip, and that the distance from center-to-center of each furring strip be 12". One of the easiest ways to position remaining furring strips is to cut a block of wood exactly 12" less the width of one furring strip and use this as a guide in positioning the remaining strips. (See Fig. 7).
All furring strips must be level. Use a long level to get a reading on all strips as they are added, and wood shims can be inserted between the joists and the furring strips for leveling if needed.
At the walls which run parallel to ceiling joists (at right angles to the furring strips), you may use scraps of furring to provide a nailing or stapling position for border tile. See (Fig. 8).