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What are you smoking? If it is poultry, I would recommend chips because you don't want too much smoke. For long smokes of pork or brisket, I prefer chunks. Everybody has their preference though. Just think of how long you are cooking and remember how many chips it will take to get a chunk. That is why I like chunks. Good luck.
Before I would tackle a brisket, I would recommend you do at least one of two things...preferably both. 1. Try smoking a pork butt. It will give you an opportunity to learn temperature control and it is very forgiving. 2. If you are just dead set on a brisket, do as much research as possible about how people do it. There are several different threads on this site that go into detail on different brisket cooks. Be very diligent. I myself have only done one brisket but the several pork butts I have done really helped in learning the temperature control.