One of the things Autodesk introduced in Maya was the interactive creation. In it's normal workmode, that means that you click and drag on the grid to place and scale your object. However, there are some extra little details that can be worth remembering.
First of all, remember that planes and cubes are created differently than other primitives. With the first click, the corner is placed and then you drag out the other corner. With the other primitives, you place the center with the first click, and then drag out the radius.
If you press the control-button when creating a cube or a plane, it is placed as above, but when you drag out the height, it grows so that it's center is at the ground plane (as compared to having it's base on the ground plane normally).
If you press the shift-button when dragging (regardless of object) it is created equally large in all directions, and it's base rests on the ground plane.
Finally, Ctrl+Shift makes a cube behave just like the other primitives in that it is created with the same dimensions in all directions, and it's center is on the ground plane.
You can also double-click instead of click-and-drag, and that creates a primitive with size (for cubes and planes) or radius (for spheres and similar) 1 in all directions, with it's center on the ground plane at the spot you double clicked.
Another little nice detail: In the menu Create -> XXXX Primitives there is an option Exit on completion. If this option is unchecked, you don't leave the creation mode when a primitive is created. This way, you can rapidly create a large number of primitives just by clicking and dragging.
From Maya 8.5 there is also a tool option that let's you adjust different parameters after creation. Create -> Polygon Primitives -> Cube (as an example) and click the square to open the options window. There should be a heading After Creation Settings. If you activate Adjust Subdivisions, you can set the number of subdivisions by click and drag when you have created your primitive.
Finally, you can activate the Snapping-funtions to snap your primitives to a grid or a live object, for instance.
