Start in the centre (approximately) of the room about parallel to one of the walls. Very few rooms are truly right-angled, and few walls are truly straight. From this tile work to each wall to form a cross on the floor, then fill each quadrant. You can, if you prefer leave the edges ragged until the end of the job, and do all the tile cutting in one go. (this also means that if you have hired or borrowed a tile cutter you only need it for one day). Also this means that you are not forever changing tasks from laying to cutting and vice versa.