There are two information centres, one in the second courtyard and one in the third where you can find out what time the changing of the guard takes place, buy tickets and get audio guides.
There are four ways to approach the castle. By far the best way is to take tram N°22 to the Pohořelec stop, where you start with breathtaking views of Prague from Strahov Monastery; then walk down through beautiful Hradčanská district along Loretánská towards the main castle entrance on Hradčanské náměstí. You can skip the Hradčanská walk by getting off the tram earlier, at the Pražský hrad stop, from where you enter the second courtyard. Alternatively, walk up Nerudova and the steep hill from Malostranské náměstí. The worst approach is up the Staré zámecké schody steps near Malostranská metro station; these are best kept for the way down.