LIQUORS:

Bourbon
Beer or Ale
Brandy (cognac)
Gin (London dry)
Rum (light)
Scotch
Tequila
Cheap Vodka (Absolut, Smirnoff)
Good Vodka (Chopin, Belvedere, Ketel One)
Rye (Blended Whiskey)
Sour Mash Whiskey
Amaretto (optional)
Bailey's
Crème de Cocoa (Must Have)
Dark or Spiced Rum
Kahlua
Peach Schnapps
Sweet Vermouth
Champagne
Sherry (dry & Sweet)
Liqueurs (Café, orange, herbal)
(Triple Sec, Grand Marnier, Cointreau)
Vermouth (dry and Sweet)
Wine (Red, white, blush and sparkling)

The number of bottles to be stocked will of course depend on the number of guests expected, their anticipated requirements, and the amount of time to be devoted to drinking (a drink or two before dinner, a three-hour cocktail party, etc.).

EQUIPMENT:

I already provide all the equipment necessary.  This is just a list for your reference.

Blender
Wine Opener
Bottle and Can Opener
Citrus Squeezer
Coaster
Bar Scoop
Cocktail Napkins
Cocktail shaker
Corkscrew
Cutting board
Dish towel
Drink Stirrers
Ice Bucket & Tongs
Jigger
Paring Knife (for fruit zests)
Strainer
Toothpicks
Swizzle Sticks
Short Straws
Cocktail Picks
Bottle Sealers
Champagne Stopper
Pitcher
Shaker

GARNISHMENTS AND FLAVORINGS:

Use fresh fruit for your garnishes. Again, it depends on what you plan to make, but this will prepare you for most cocktails. You can use your imagination and add fresh fruits, candies, sprinkles, or even tiny umbrellas to give your own personal touch to your creation.

Citrus, (Lemons, Limes, Oranges) (whole, slices, wedges or Peels)
Coarse Salt (for Margaritas)
Cocktail onions (for Gibson)
Cream of coconut (for piña coladas)
Celery
Olives (for Martinis)
Maraschino Cherries (for Manhattans and Old-Fashioned)
Simple syrup (for sweet cocktails and punches)
Cocktail Onions
Whipped Cream
Powdered Chocolate
Salt & Pepper

Mixers::

Stocking mixers is like stocking your alcohol.  It really depends on what you plan to serve.  This list will prepare you for most any cocktail. 

Sour Mix can be powdered, bottled or in concentrate form.  Bloody Mary mix is not necessary if you aren't making a lot of them.  Piña Colada mix can be made yourself with pineapple juice and a cream of coconut, such as Coco Lopez.

Orange Juice
Cranberry Juice
Pineapple Juice
Grapefruit Juice
Tomato Juice
Sour Mix
Bloody Mary Mix
Piña Colada Mix
Bitters
Lime Juice
Grenadine
Simple Syrup
Worcestershire Sauce (for Bloody Marys)
Tabasco Sauce
Hot-pepper sauce (for bloody Marys)
Strawberries
Bananas
Club soda
Tonic (quinine) water
Tomato or seasoned
Cola (Coke or Pepsi) 
7 - up
Ginger Ale
Diet Cola
Half & Half
Milk
Ice Cream
Coffee
Water (Sparkling and still water (flavored and plain)

ICE!  Plenty of Ice