Reference setup

Hi abhi ,

Using a scaled Cube as a 'bounding box' for your models is usually (always?) a good idea.

If you are in the luxury to have orthographic views as reference, you can re-size them to match that 'cube'. Mind you, that more often than not, those references do not line up perfectly; then it's a good idea, to use one of them for the 'exact placement' of the features and the others more as guidelines.

Very often, you'll just be using reference photo's, (from different angles), or even just a single image. They are typically not even placed in the 3D Viewport, but in an Image Editor Window on the side.

Find your own ways and learn to work with what you got; it all comes down to experience, which comes through practice, practice and practice.

Exactly as Martin says, it just comes down to preference and what you have available. In the end it's up to your own liking and as you gain more experience you use whichever method or any other that works for you to accomplish the task.