Stay away fromanything citris (lemon, grapefruit, orange, mandarin) and don't use the leaves, they'll taint the flesh.

By all means use sawdust from fruit trees like apple, but Ti Tree still works the best for me.

Some shops sell hickory and other types of sawdust, take a look at the BBQ factory shops, I think they do a range. They do make a good smoke with the right flesh. Don't overlook smoking breadcrumbs for the fishcakes, or beef steaks before grilling them. Whole chook smoked for an hour before roasting puts a great flavour through as well. Not to mention boiled eggs placed in the smoker and sent through with the fish tasts nice. Gives my wife a surprise whenever the smokehouse is finished, she doesn't know whats going to come out each time!

Ross