Shoulder is hard to mess up, so it might be a good choice for a first cook. As long as your temps stay in the 225 to 290 range, you should be good to go.
Personally, I only need about 12 - 15 briquettes poured on top of a chimney of unlit briquettes, but you might need more for a longer cook. I also use a diffuser.
Go for it! Just keep your temps under control (which should be easy with a UDS) and you will be fine.
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