Also, if disgression is not such a problem, you can always zoom out into object mode, and add the modifier 'bevel'. It will apply it to the whole model, but if you rework it afterwords, you can smooth edges with less faces, and it is very precise. You can modify how big the bevel is, so you can take a low poly, boring model and make it fantastic quickly. Just remember to save, because this can ruin your model if you do something wrong. That, or make sure you undo.