You don't say if it is a concrete floor or floorboards and is the kitchen at right angles to the hallway?anyway the straight line from the door to the kitchen has to be perfect it may differ on the sides(and will)thats life, your eye follows the centre line of the floor,this is PARAMOUNT,buy a chalk line from any DIY(a metal reel full of blue chalk)find the centre of the doorway bang a nail in,hook the chalk line on it,walk back to the kitchen's furthest wall,put the chalk line on the floor pull it tight,eye it up straight and "Ping" the line on the floor,it will leave a long blue line on floor to work from,if the centre line ain't square to the passage it will look crap,the laying/gluing thing is another story,it should be nailed!
Rich, January 2008