I hear questions regarding business dinners from friend all the time. This can be a make or break situation for you especially if there are outside clients or senior staff at the table.
The biggest piece of advice I can offer is "play it safe"!
If you are a junior team member be careful about ordering alcohol and never order alcohol first. If everyone at the table orders then it's acceptable but don't put yourself in the position of being the only one with a beer/wine/cocktail. Picking the type of drink depends on the company at the table, the restaurant, and the fare. Generally when ordering a beer I order something besides a Coors/Miller/Bud (Lite), to me these beers are still too close to what you drank in college and can still hold those connotations. I would order either a local brew, standard lager or IPA, this way a bit of sophistication comes out even in your beer choice.
As for wine, the decision really comes down to preference and fare selection. Of course if you are having meat with the meal a red wine is the best choice. I would recommend getting and reading a wine for dummies book if you plan on having a lot of dinners with wine in your new position, it could go a long way. Also red wineglasses can be held at either the stem or as the base of the bowl because reds are served at room temperature. A white on the other hand is served chilled so you only want to hold the glass by the stem so as not to warm up the wine.
For a cocktail stick with something classic not new and fancy. Here is where you should have an idea of what you like, also know the terminology i.e. neat, up, twist, dry, etc. I will elaborate on these points in an upcoming post.
When it comes to the meal, unless it is a VERY casual and laid back dinner do not order anything that requires you to use your hands and pick it up. Pick a dish that requires a knife and fork, and do not cut the meal with the side of your fork; learn to use both the knife and fork in a proper manner.
Be careful what you say, even though you are not in the office what is said at dinner can have lasting affects. You never know what you might say that could offend a client or boss, you do not know his background and he may view and think of appropriate conversation completely different than you do.
Those are just a few quick tips for eating out in the corporate world, I have witnessed some blunders in this area and it can sometimes be very difficult to dig yourself out of a hole you dug at a dinner.