I do not make my own haggis - the smell when cooking it from the raw state can be off-putting. I buy directly from my local butcher (who makes his own) or a MacSween's haggis - which is the best commercially-available haggis in Scotland (IMHO).
Here's a recipe for haggis which I posted here a while back. It's taken from www.rampantscotland.com
This from www.rampantscotland.com
Set of sheep's heart, lungs and liver (cleaned by a butcher)
One beef bung
3 cups finely chopped suet
One cup medium ground oatmeal
Two medium onions, finely chopped
One cup beef stock
One teaspoon salt
½ teaspoon pepper
One teaspoon nutmeg
½ teaspoon mace
Trim off any excess fat and sinew from the sheep's intestine and, if present, discard the windpipe. Place in a large pan, cover with water and bring to the boil. Reduce the heat and simmer for an hour or possibly longer to ensure that they are all tender. Drain and cool.
Some chefs toast the oatmeal in an oven until it is thoroughly dried out (but not browned or burnt!)
Finely chop the meat and combine in a large bowl with the suet, oatmeal, finely chopped onions, beef stock, salt, pepper, nutmeg and mace. Make sure the ingredients are mixed well. Stuff the meat and spices mixture into the beef bung which should be over half full. Then press out the air and tie the open ends tightly with string. Make sure that you leave room for the mixture to expand or else it may burst while cooking. If it looks as though it may do that, prick with a sharp needle to reduce the pressure.
Place in a pot and cover with water. Bring to the boil and immediately reduce the heat and simmer, covered, for three hours. Avoid boiling vigorously to avoid bursting the skin.
Serve hot with "champit tatties and bashit neeps" (mashed/creamed potato and turnip/swede). For added flavour, you can add some nutmeg to the potatoes and allspice to the turnip/swede. Some people like to pour a little whisky over their haggis - Drambuie is even better! Don't go overboard on this or you'll make the haggis cold. At Burns Suppers, the haggis is traditionally piped in and Burns' "Address to the Haggis" recited over it.