How specific do my travel plans have to be for getting a Schengen?
When you apply for the visa be very specific about your travel plans, in your itinerary include many things which you are going to do in Schengen zone. For example, Dinner on cruise at night in Paris, Zip-lining in X country, Cycling in Amsterdam, Or about doing drugs in Amsterdam. (No, don't say that) In your cover letter write that how much this trip means to you and be specific about your interests in those countries. May be you are interested in arts, museums, architecture or anything else try to make purpose of your trip clear. By doing this, youre escaping a very common reason of visa refusal which is the purpose of the trip isn't clear. You do not need to show your inter-Schengen transportation tickets so buying train/bus tickets is not compulsory but, you do need to show hotel bookings for each and every day of your trip. You can say that you will buy trains once youre in X country but, you can not say that for hotels.