There are any number of possible adjustments to make but the most common are these:
- cup shape, which can be adjusted by changing the curve of the top of the cup lower piece. A small adjustment here goes a long way so change an eighth of an inch at a time, and make sure to smooth out the lines well. If you have to make a lot of change here you'll probably also need to adjust the cup upper as well, making it slightly longer or shorter to accommodate the difference in length of the lower cup edge.
- center stay. May need to be shorter or longer, depending on how widely placed your breasts are. You may also find that changing the angle of the sides gets you a better fit, either straighter or more flat of a triangle.
- cup top edge - I found I wanted my bras to be slightly less than full coverage, so I lowered the outside edge of the cup (but not the inside edge). This also meant I had to make the straps longer to make up for it.
- side/back too short or too long. Make adjustments to this piece in the underarm area.