To Begin:
First - decide if you’re comfy and old enough to wok with alcohol or not. If you’re not comfy or old enough, this may limit your options a little.
Check out the local restaurants that you want to work at and see if you can get a copy of their menu. Learn all you can about it. Also, check out how their servers operate. Are they allowed to carry around a notepad or pen or are they required to remember the order. Either way, find some memory tricks to help you remember people, faces, specials and orders, especially drinks.
Second, practice your face to face customer service skills with the people around you. Have them play a variety of customer roles i.e. the quiet customer, the obnoxious customer and the difficult customer. Find ways to keep your cool and relax in any situation that may arise.