The best way to improve conversational skills is to engage in conversation! Join a non-academic club on campus that interests you. Dancing, sailing, singing, ect. If you have a common interest with a person it is much easier to strike up a conversation. If you don't have any interests, join clubs anyway! It's the best way to make new skills and find out more about yourself. I recently joined a Swing and Ballroom dance club and it's great because we only meet one day a week for 2-3 hours. I'm sure there's something out there for you.