At the very least, separate the bar/ beverage area from the food area. Browsing a buffet is a different speed than dashing off a martini or pouring a glass of Chianti. Plus beverage areas involve sloshing, splashing, ice, lemon wedges, and all manner of things that you wish to keep cold while you want to keep food room-temperature-to-hot. Separate the bar from the food.
If you have the room, separate the canapes and desserts from the main food area especially if your party is more of a cocktail reception affair. Spreading the different courses through the space encourages mingling with minimal effort.
But, back to the bar.
A good self-serve bar needs:
Glasses that match the offerings (wine glasses, rocks glasses, highballs, cocktail glasses, etc.)
If you are serving cocktails, set your bar area near a sink so that cocktail shaker ice can be easily poured away. Alternately you can pre-mix a batch of a signature cocktail (Moscow Mules, Bloody Marys, Gold Rushes, Margaritas, Mojitos, Brambles, and Smashes all work beautifully), pour into a pitcher and set beside a serving a note (“Pour over ice and add a squeeze of lime”, etc.)
If you are setting a full service bar for cocktail service, place like things with like– wine with wine, spirits with spirits, mixers with mixers, garnishes with garnishes, tools with other tools. Corral your tools (bar spoons, wine key, bottle opener) to a small dish or tray so it is clear where to look for them.
In addition to an ice bucket, it is a good idea to provide a small, elegant receptacle for bottle caps, corks, wine wrapping.
Return to the bar area periodically to tidy up, refresh ice, empty the debris bin and stock with fresh glasses.