Everyone likes to think they have good table manners, and I am no different.
The only thing I was in trouble about as a kid was wanting to sit at the table without a shirt on. This apparently, even in Australia when you're 11, is a no go. Everything else I did at the table I did quite acceptably: no elbows on the table; I tore my bread roll rather than cut it; and I even used my knife and fork in the "correct" hands. (For readers in North America, this meant my knife stayed in my right hand, my fork in the left, and I cut my food as it became needed.)
Except for one thing.
It really isn't done to put your hands below the table. If you're from the USA and some parts of Canada, this means forgetting what your mother told you, and keeping your hands above the table. Sitting like a lady with your left hand in your lap after cutting your food isn't likely to really cause real offence (you're foreign, and probably can't help it), but all the French people at the table will spend the whole meal wondering what you're doing with that hand they can't see. Especially if you're sitting next to someone else's husband...