I'm definitely not the kind of person to start up a conversation. I'm perfectly capable of carrying one on, I just usually have a mental blank on things to talk about that would actually interest the person.
Although, I can start one up if the person I'm talking to is more shy and awkward than I am. (Unlikely ). I pretty much just ask if they did their homework, or if they find something hard if I'm in class. Or, if holidays were nearby, I'd ask what they were doing. xP