The key to cooking a snag, whether on the barbecue or in the frying pan, is a moderate heat and making sure you rotate them evenly.
DO NOT attack them with a fork, you should never burst their skin while they are on the grill, you’ll let out all the moisture and flavour. A quality sausage shouldn’t have too much fat in them. If the skin bursts then you’ve overcooked the sausage on too high a heat.
Chunky sausages should be cooked slower and put on a few minutes before the rest. When cooking on a BBQ put your sausages on first at a low temperature to heat through, prior to increasing the temperature for cooking your steaks.