Some basic rules in Maya

I made this 3D scene in Maya,

for a Christmas card, and I notice there are some tricks to know when you are working with boolean operation from polygons/mesh/booleans. Working with booleans is simple, first select the children (object what will be modified), pres Shift and select the parent (object what will do the modification) and chose from polygons/mesh/booleans the operation, if you want to make a hole chose: difference.

After the operation is done, you still can modify the dimensions of the objects involved, if you click on outliner (window/outliner) on the initial objects (not on the new shape obtained) and from channels you can do the modification.

 

For more output options when you work with booleans, or if something in not working properly, check the normals for the objects involved and try different settings. To do that, first select the objects and make normals visible from Display/Polygons/Face Normals (if you want to make them invisible repeat this step) and with only one object selected go to polygons Normals/Reverse. Now try different combinations with normals and booleans until you will be happy with your result. Attention, if you want to bevel the objects make this operation before any boolean operation because after that you will have only errors. If you want to modify later some geometry in the resulting shape, is highly recommended to bevel objects first because all faces which are not involved in the booleans operations will be fully editable.