Try relaxing your vocal cords, make sure you dont get strained.
Try saying mum...Mum....muM in different tones instead of do-re-mi. Warm up for some minutes before starting to sing.
Drink lots of water, avoid taking ice, a hot /warm tea should do it.
This really helps your Vocals cause its hydrates it and create ways for your mucus...
Cold water will only tighten up your Vocals.
Also avoid taking Milk and softdrinks cause it allows mucus to build up in your throat
Make sure you dont hurt your voice, dont over stretch your voice, Just try to keep your voice low and calm.
Avoid shouting, Screaming and un-necessary arguments
Try doing some exercise, Doing so makes you breath deeply.
Make sure you are breathing deeply not just gasping.
And finally when you sing, Sing with lots of confidence and always believe in your self.
Trust me, you would make a fine singer.