Hi 7outof10! Thanks for posting, be sure to introduce yourself at Roll Call when you get the chance. We'd love to know a little about you and your equipment.
If you're dead set on sliced beef, then in my opinion it's gotta be brisket. If you're new to smoking then you need to search out brisket in the search panel.
Keep your smoker temp around 225º to 275º. Smoke the brisket to a temp of approx 170º internal temp. There will most likely be a stall where you think your thermometer has quit working.. just let it keep on smoking (without turning the heat up) until the temp starts to climb again. At that point double wrap the brisket in foil and cook it on up to approx 190º internal temp. Remove from smoker and let sit for at least an hour while the juices redistribute. Slice and enjoy. (Cut down simplified version)
You will need a good thermometer for checking the temp of your food. You also need a good thermomter (oven thermometer that sits on the grate is fine) for your smoker to know where your smoker temp is at. Don't cook by time - Always cook by temperature. Never rush a good smoke! It's done when it's done. To figure when you need to start (just as a guide only) allow 1.5 hrs per pound plus 3 to 4 hrs to allow for stall and resting.
MOST IMPORTANT - Never push the smoke to white billowy smoke. Always think Thin Blue Smoke... almost invisible. If you can smell the smoke or it burns your eyes when you are over the smoker ... it IS smoking.
Any questions feel free to ask.