finger counting

I'm not sure it's all of Europe but, yes, in Germany your thumb is number one. Holding up one finger in a loud stube might get you two drinks. Usually they know you're American and don't use the same custom, so they know your one finger means one.

They would still understand if you hold up four fingers as we normally do here.

I have never held my fingers in any special position when asking for a table, etc. When you hold up 4 fingers, they can obviously see 4 fingers. Don't stress out on this. No one is ever, ever going to care about this. To be honest I have never even noticed anyone doing this, perhaps with 2 or 3, but never with 4.

Either I was told or I read somewhere that you do have to be careful about holding up fingers when ordering drinks, that if you hold up two fingers to order two beers, you might get three because the European bartender may assume your thumb is extended too. I have been careful about it on trips to Europe. Glad to hear that it's not an issue.

This is an interesting question! Did you try your other hand? I can hold up 4, starting with th ethumb (pinkie down) with my right hand just fine. But not with my left, no way. Actually we just learn to ask for what we want in the local language, so no hands involved, but that wouldn't work in a country where we can't do that (anywhere in Eastern Europe).

aubergine, THIS website provides a short tutorial on some of the hand gestures to be careful with. This is by no means a comprehensive list, and some gestures are specific to country or region. The one that you'll probably use when ordering drinks is with two fingers, so be sure that the palm of your hand is facing the correct way. Cheers!

Or learn to say "four, please" in several languages...

You start with the thumb and the thumb is included from one to three. However number 4 uses the 4 fingers except the thumb. For number 5 the thumb reappears again.
For number 6 and above you need the other hand, unless you are an extraterrestrial alien with 6 fingers.

Ouch! That hurts. I think I just pulled a muscle in my hand attempting that manuever. (Some how I've been getting the message "four" across. Probably verbally or in the good old American way. Has never caused confusion, as far as I know.)

I could see you potentially having a problem with making a "2" or a "3" if you don't make it in such a way that your thumb is clearly not included. And keep in mind that you put up your pointer finger to indicate you want to get called on, or that it's your turn, in France. You don't raise your hand like we do in the US.

Why don't you use both hands? Show two fingers with each hand.