Hey Lavanya,
I completely agree with Nishthha, proper breathing pattern is a very important factor to be taken care of while lifting weight. Never hold the breathe as it can cause increase in the internal pressures of the body which can lead to hernia, faintness,dizziness or even damage eyes.Take several deep breathes before lifting the weights.Now,exhale when you lifts weights and the exhalation should continue till the muscle contractions lasts.Start inhaling as you bringing the weights down to their original position.