You should plan your trip to Iceland well in advance. Since the country is small, touristy, and hotels are seldom empty, you need to secure yourself a place to stay, preferably a year before the trip. Iceland is not one of those countries that you can go to spontaneously because upon your arrival, you run the risk of not finding accommodation, especially during the season. There's, of course, an option of staying at campsites, but it's only possible in summer. And even then, living in a tent can be quite uncomfortable, to say the least, particularly during steady rains.