I have never sanded drywall. My uncle, a building contractor, taught me to use a 5 gallon bucket of water and large rectangular sponge. With the sponge wet and wrung out just enough so it doesn't drip, wiping the joints lightly from side to side removes the high spots. Don't scrub the joint, and don't keep wiping it in the same spot because the taping compound on the seam will become too soft. Wet and wring out the sponge often, so it's texture removes the high spots of the compound. Come back later if you can't get it right without getting the joint too wet. Let it dry and then come back for a second pass after it has dried.
When taping the joints, it's best to apply a heavy 1/2" layer, add the tape, and then squeeze out most of the added compound. Let it dry and then use the taping knife to scrape off any high spots before applying a second coat. It helps to have a curved (not flat 12") trowel for this pass to gauge the amount of compound left behind. A bright light on a stand at the working height and close to the wall will let you see how level and even the joint is. I do this if an additional touch-up thin coat is needed to help smooth uneven areas.
While wiping the joints smooth with the sponge I've found that wiping the compound filled sponge across the the surface of the paper on the whole surface of the sheets leaves just enough compound on the paper surfaces to make less of a difference in surface texture between the seams , so the first coat of priming paint produces a smoother surface and less visible joint areas. If the result isn't nearly flat enough I may go back and add another thin layer using a wider curved trowel (14 or 16") before sponging.
2 days or more later is when I go back with the sponge and bucket of water, again using the light close to the wall so it's light shines across the joint. Sometimes a third coat is needed before this final coat, especially if you needed to fill areas of wide gaps between the sheets. I may just do these areas again and scrape the high spots
again before doing the sponge and bucket step. This light scraping needs to be done after every coat of compound has dried and is firm.
There's no dust to breathe during this process when doing it this way with a sponge, but it does require a bit of practice to get really good at it. I have helped build several houses with my uncle and then remodeled two houses that I've lived in and have always gotten better results than many of the contractors did without filling my lungs or the house with dust. Sponges are lighter, even when wet, than any sander too.
Oh, when first learning to do seam taping and compound application on drywall, it helps to have a little wine about 20 minutes before starting. Without it you will be too fussy and keep trying to get the joint perfect on the first application. Getting it close is great, but don't keep messing with it. Scrape the high spots with taping knife before applying the next coat, which will fill in the low spots. Again, scrape the high spots after this application dries and before the next coat is applied. Do this every time. It may take 3-5 thin coats to get good results until you get better at it, and before the sponge treatment. You will improve quickly though, and get much better and faster with experience.
Charley