It's not quite as simple as just the maximum voltage and current, you also have to consider power dissipation, especially if the transistor will be operating in its linear region. Multiply the expected current with the expected voltage at that current to get the power dissipation, ensure this is below the maximum for the transistor. This is less of a problem for a transistor used for switching because it's either on: high current low voltage, so low power dissipation, or off: high voltage but low or no current, so little or no power dissipation.