Depends on the obtect to be cut around. Large stuff like toilet basins I tend to use a "transfer piece" basically a cut full length piece off of a
tile and setting the
tile to mark on the
tile adjacent but behind (if you know what I mean) run the cut piece around the curve marking the
tile to be cut with a pen or pencil at various points. It is essential to keep your marker piece parallel to the edge of the
tile being marked as you go around. You can then see a curve the same shape as the object to be cut around on the
tile. Adjust the position of the curve on the
tile to take account of the grout line and cut along this new position.
Sounds long winded but is really quite quick once you have done it once or twice.
Grumpy