Lakshya,
We're going to need more to go on. Sounds like quite an undertaking if you have a limited amount of experience.
Tell us about the arm--make and model if you have it or was it home-made. Could you post a picture?
Is the pick and place application forever the same picking and placing or do you need it to be programmable and to change from time to time?
What are you trying to pick and place?
Do you have a tight budget and a lot of time or a lot of money and a little time?
Is this for school, work, or hobby?
Thanks,
Dale