How to get a better orientation for my Model when uploaded.

This is where placing the first part in an assembly model is so important. It also helps when creating your individual parts to start the first sketch centered on the origin point of which ever sketch plane you use. A little forethought goes a long way in how your models presents. Also, when you create your part models, your sketches should be fully constrained. I also agree with the first answer as far as uploading images of the model as this is the best way to showcase your work. I use Inventor studio to render my models, with multiple views, then upload the jpg files to show the model. As for the stp file or what ever formats I upload, it's up to those who download the models to place and orient when they import and convert to their software. Hope this helps.

Straight on is a pretty fortunate outcome.
When I upload models they are sometimes turned on their side.

I assume the default orientation results from how GrabCAD interprets the coordinate system from your CAD software. If your model is always straight on, then try exporting the Step file with a new coordinate system which is rotated 45° about the vertical axis.
Some trial and error may be needed to get the ideal settings.

But, the orientation of the CAD model is somewhat unimportant. The better approach is uploading a separate image file which will be the main view in the library. Rendered images are usually the best, but even a screenshot of the model will usually look better than the stock image generated from the imported CAD model.