12 inch inch spacing with 30 inch rows works well for me. Hilling will increse the yield as tubers are formed above the roots. Hay or straw works well, leaves also work but you may have some problem with matting, which can cause wet spots in a rainy season and increse tuber rot. Saw dustis usually not a good choice as it pulls nutrients especially nitrogen from the soil doing its decomposition process. Grass clippings work pretty well.

Thanks farmerdilla, I'll be carful not to use saw dust.

but I can't seem to get a straight answer as to how exactly I should space them.

I think it all depends on how you plant them. If you trench and then hill them as the commercial growers do you can plant more closely together than if you just hole plant.

I dig a 6-8" deep trench, plant the cut and healed seed potatoes 8" apart with rows 2" apart. That leaves just enough between the rows to keep hilling them with dirt and straw through their growing season.

As farmerdilla said, hilling will definitely increase your harvest and avoid sawdust. Hay works with some soil mixed in as does straw also with soil mixed in as nutrients are still needed by the plants. Compost works well too or shredded leaves so that they don't mat down.

Check out the pictures violet posted in the clipping linked below. They are a big help explaining how to plant potatoes.

Dave

Here is a link that might be useful: How to grow potatoes