I will be arriving at Frankfurt airport August 29th and would like some help knowing the best way to travel around. My short stay in Frankfurt ( Frankfurt Messe) will include a trip to Selters then I intend to go to Boppard. From there to Cologne and from Cologne to Brussels and back to Frankfurt. Would it be best to buy individual tickets for each of these journies by train? Or is there some kind of ticket that would cover my travel , at least inside Germany?