how to keep conversation rolling with a girl?

[Mel]

From what I know, girls love being asked questions. After she's replied, maybe ask her something related to the topic--you'll be surprised as to how conversations develop over just the smallest questions or comments. If she's interested in what you're talking about then I'm sure she'll try to keep the conversation going as well.

However, if she only briefly replies to your messages with one or two words, then I suggest that you just drop it for a while. You don't want to make her fed up. But, like I said, I'm sure the conversation will come easily enough once you've got the ball rolling. It might just be nerves which stop you from messaging her, and I know it's hard, but try to forget about that and talk to her, if that's what you really want to do!

As to the question about only messaging her when she's online, I really don't think it matters that much. I doubt she'll think too much in to it, and by the question you're going to ask, she sees that you have a reason for messaging her, so I think you'll be fine.

Hope this helped, and good luck!