Well, that may depend a lot on the person throwing. My darts are cane with hardwood foreshafts, about 6'6" long. the nock end is roughly the same size as an arrow shaft, the thickest part is roughly a half inch. I taper down from the last node and through the foreshaft until the point area is about 3/8 of an inch. I have 125grain field points glued on mine to practice with. my hunting points will likely be in the 125-160 grain range. I throw it just about as hard as I can so mine are pretty stiff spined. Just like arrow shafts they have a weak side so to find this I put the point end of the shaft on the floor and nock end towards the ceiling. Then I put the thrower onto the nock and apply pressure downwards until the shaft flexes.... this will show you the weak spined side of the shaft.. I put the "cock" feather on the weak side and orient it up when throwing. You want the weak side in the same place everytime to get consistent throw and want it facing up so the shaft is flexing naturally when you throw..this keeps the shaft from wanting to roll when thrown. some folks can throw shorter darts... but i really struggle with the short ones
