When you're using Blender's hotkeys to transform objects, where you place your mouse cursor before performing the operation can be pretty important. Although the importance of your mouse cursor's location has reduced a bit with the new continuous mouse feature, cursor placement can still be an issue, particularly for rotating and scaling.
For rotating, it's a good practice to keep your mouse distant from the object's origin. Doing so gives you more control over how you rotate. If your mouse cursor is too close to the center, you can have your object spinning in all kinds of unpredictable ways.
The same is true for scaling, but it's more dependent on whether you're scaling up or down. If you're scaling up, it makes sense to bring your mouse cursor a bit closer to the selection's origin so that you have more control. If you're scaling down, start with your mouse cursor farther away from the selection's origin and, as with rotation, you have more control of how small your object can get.
For grabbing, it's a bit less important, but I generally like to have my mouse somewhere near my object's origin.