Stop by the tourist information center - across from Central Station - they have a publication called "This week in Copenhagen" that lists the various museums and what their opening hours are. This is important since many are only 10-17 (10-5) or less. Some museums are open late one day a week, that can be a useful part of your planning. Some also have a day with free admission, listed in the guide. There were also many other useful booklets.

 While the Copenhagen Card offers admission to many attractions, plus free public transport, the short museum hours could limit how much you do in a day, and whether the card is worthwhile.