To foil or not to foil. Generally when you read about foiling on these threads it's in regards to ribs. You can do some browzing and searching and you'll find tons of threads.
The 3.2.1 method for ribs: Cook for 3 hours naked, 2 hours wrapped in foil, 1 hour naked. IMHO foiling isn't necessary on a UDS.
Honestly tho, if this is your first UDS cook. K.I.S.S. Keep it simple....
Cheap, quick, hard to screw up... go with a whole chicken. Buy a whole chicken, rince, season lightly and load it up.
When I've seasoned new UDS I typically wash out the drum with hot and very mildy soapy water, rinse a couple more times, thoroughly dry. I spray the entire interior with a light coating of olive oil. Fire up a basket about half full of your choice of lump or briquettes, toss in a couple chunks of your choice of smoking wood (I prefer hickory and/or apple).
Work with the temps, adjust, babysit - find your UDS's particular quirks during this seasoning burn. If you've built a basic UDS from all the tons of intel here on the Brethren you should find a happy medium pretty quickly. Try to get your temp stable (I do 99% of my smoking at or about 230 degrees) and let it smoke.
Get that target temp dialed in and leave the thing alone! Don't lift the lid to peak, don't adjust things just to adjust things.
In my experience you're looking at about 1 inch of air intake on the bottom and 2 inches of exhaust on the top (assuming a 55 gallon drum). Remember to be sure your exhaust is always 150% or more of your intake. The natural process of heat rising with feed your fuel fresh air and the larger exhaust will keep things flowing in the right direction.
One thing to watch for that I don't always see mentioned? Wind direction. I usually make an effort to insure my air intake openning is on the opposite side of the UDS, shielded from any wind. This avoids having the wind pumping/forcing air and higher temps.
Once you've done a seasoning smoke/burn you'll know a bit better what to expect from your UDS during an actual cook.
Smoking a chicken for a first run is a simple and cheap option IMHO. I'd much rather screw up a 4.00 whole chicken than 20.00 worth of ribs.
My K.I.S.S. chicken:
Whole chicken, rinsed, patted dry with a couple paper towels (inside and out)
Season interior with black pepper. Spray interior and exterior of chicken with a light coat of Olive Oil. Lightly season outside with a little black pepper.
I keep it as simple as possible and let the smoking process bring the flavour not rubs or injections.
I generally smoke with applewood, although being in the midwest hickory is big here too.
I fill my charcoal basket about 50% with Kingsford briquettes and 50% Royal Oak lump. I prelight all my charcoal and lump til basically grayed, then choke by my temps in the UDS. Once I have a stable 230 degrees (generally only takes me 20 minutes or so too stablize) I add about 1/2 cup (a handful) of wood chips to the top of the charcoal.
Put in the cooking level grate, throw in the whole chicken breast side down. After about 1.5 hours I open up the UDS, throw on some food handling gloves and I flip the whole chicken over. Let it cook/smoke for another 1.5 hours.
Most of my K.I.S.S. chicken UDS smokes only take about 3 hours to complete, sometimes closer to 4 hours (depends on the size of the chicken).
Check the breast meat with a thermo: 165 is USDA done for poultry, altho I typically shoot for more of a 175.
IMHO the UDS is a sealed enough system that my K.I.S.S. chicken doesn't dry out cooked to 175. It's usually lightly smokey, fall apart done, and wonderfully/simply delicious.
Anyways - go with a bird. If you screw it up you can always take it inside and throw it in a pot, boil it til it falls apart and make some smokey chicken soup!