When a room has several odd angles or out-of-square walls, trying to square the tiles to one specific area often results in calling more attention to the other areas. To prevent this kind of problem, consider creating a balanced layout from the center of the room so that the cut tiles arranged around the perimeter of the room are all the same size. Locate the center of the wall opposite the door by which you enter the bathroom and snap a chalkline to the opposite wall. Snap a second chalkline perpendicular to the first so they intersect at a 90-degree angle in the center of the room. Lay out your tiles from this point, adjusting them as needed to create a balanced layout that does not follow the lines of the room's perimeter.
Small bathrooms often have the effect of catching the eye on the first thing you see as you enter. For this reason, it often makes the most sense to determine the most visible area in the room and square the tiles to this wall or surface. This may mean using a full set of tiles against the wall you first see when you enter, or a full set of tiles directly in front of a tub, shower or vanity. Lay the first full tile in the center of the wall or fixture you select, then move the tiles out evenly in each direction from there so the first thing you see when you enter the bathroom is a row of full, square tiles, not out-of-plumb cuts.
Part of a dry layout involves adjusting the tiles so you don't have small, cut tiles lining the edges of the room. While every tile installation will have some cut tiles around the installation's perimeter, in a room with odd angles, a cut tile that is too narrow will draw attention to the angle of the wall. If you have a severe angle anywhere in the room, try arranging the tiles so that nothing smaller than half of a full tile lands next to it. This will move the straight grout joint out far enough away from the perimeter so that it does not compete with the angled edge.
If you have a large, open area in the center of the area you are tiling, consider squaring this section off with a border that will direct attention away from odd angles. Tile rugs or tile accent areas help to add detail and interest to the room, while also drawing your eye away from the edge of the room. Install one or two full courses of tile around the perimeter of the area, then install a border and fill the center in with a contrasting tile, tile mosaic or tile art pattern to focus the eye.