Avoid autumn. Russia can be pretty depressing place in October and since all Russians naturally are...Mud, the leaves are almost gone, it is not winter yet, but it's already freezing. You'll depress the audience with October. Try February. It's nice. The air is so clean and crisp. Snow. Or April. It's offer hope after a long winter. April is beautiful and very easy. July is cheerful too. Whatever "song" you'll choose, do not play Song of the Lark. I think it is like Russian Fur Elise, except no one ever dreams of playing it.