I'm currently, as many of you, working on my first startup. Things are getting better and better, but now I think I should better have some kind of ticket system for communicating with customers, etc.
Now I could use some system like OTRS, Kayako, Request Tracker - or an hosted one like Zen Desktop.
What would HN recommend me?
I hate to advise that, but that's just my experience with it. That said, your need is only in proportion to how much your tickets/communication with customers affects your revenue.