Generally expensive. Hitchhiking works pretty well. Taking passenger trains without a ticket is pretty easy and usually without any consequences even if you get caught (you will probably just be kicked off the train).
There are a lot of free or very cheap campsites in Denmark. See the list from VisitDenmark.
Usually free good wifi available near universities, libraries and public spaces.
Extremely rentable. Danish crown is probably one of the most valuable and most expensive currencies in Europe. You have coins for 20crown which is around 3€, you get 3 is 10€..even though you get more often 10 (for which still you need 6 pieces). A ggod busking day can be like an average working day, which is usually very well paid.
Very good for saving money.
Denmark is a very wealthy country in Northern Europe.