1. Привет, русский! (Privet, russkiy!) - This is the most direct translation, meaning "Hello, Russian!" It's informal and can be used when addressing someone you know is Russian.
2. Здравствуйте, по-русски! (Zdravstvuyte, po-russki!) - This means "Hello, in Russian!" and is more formal than the first option.
3. Привет! Говорите ли вы по-русски? (Privet! Govorite li vy po-russki?) - This means "Hello! Do you speak Russian?"
4. Добрый день! Вы говорите по-русски? (Dobryy den! Vy govorite po-russki?) - This means "Good day! Do you speak Russian?" and is even more formal than the previous option.
The best option to use depends on the context and the level of formality you wish to maintain.