We dig two long trenches, lay the seed spuds in the bottom, cover them and earth up as necessary. We also give a final mulch of well rotted manure (safe stuff lol) after having watered well. This, together with the top foliage which by then is rampant, keeps the tubers from drying out.
We have had fewer problems with potatoes growing (apart fron blight) than any other veg.