I prefer alternating the points, but it's your quilt and your choice. To my way of thinking, one of the harder things about a friendship star, of which I have made a great many, is keeping the points within a single star consistant. for that, I suggest laying out the subunits as they will be, then working you way through them, row by row. When you are making a whole bunch, it is easy to have one that goes gallywonkers.