Can serial communication pins (Tx0,Rx0) in Arduino Mega can be used for normal digital communication (like for blinking LEDs etc.) ? If yes then is there any different approach or commands that I need to include in my code or defining them normally as other pins is enough ?
That's all you need.
And don't use Serial.begin() in setup().
For many Arduinos, including the UNO, having circuit elements attached to the serial pins makes it impossible to program the Arduino. You have to unplug it from the circuit to upload a new program.
Serial communications is so useful during development and debugging, it's an extremely good idea to keep those pins available for serial. But they are general-purpose pins, so you can do whatever you want with them, like the other pins.