This is obviously very common for Tour Players as they are getting ready each week to play at a different course. This can also occur for amateurs as well if they have an interclub tournament or if you're deciding to play with friends in a competition format. The preparation is obviously different depending on the importance of the event.
For my example the biggest aspect I would do to prepare for another course would be to play a practice round. Try and do this practice roughly a week before the competition as the conditions should be fairly similar to that on game day. These conditions include green speed and firmness of the fairways. Obviously rain and wind can affect this on game day but you'll get quite a good idea what you're in for.
When doing a practice round it's not so important on trying to shoot a low score but getting a feel of the layout of the course. More specifically what you would do on certain tee shots. For eg. will you hit driver, 3 wood or iron off the tee? When making a determination of what you would hit off the tee, it would all come down to where certain bunkers, water hazards, Out Of Bounds posts and obstructed trees are placed. Using a range finder will give you the exact distance and hence help you in your final decision. For eg. If a bunker is positioned at 250 m in the centre of the fairway and you know you hit your driver 250m, you may decide to hit a 3 wood or iron instead.
The other important element is testing the different breaks on the green. As you are not sure where the flag will be, start hitting putts from different locations and make notes. These notes should include green speed, breaks and whether the green is elevated or not. Also make a note of the correct portion of the green to hit the shot as it may not be favorable to aim the shot directly at the hole on game day. Always hit the shot onto the green where you will have the easiest putt which is often uphill.
If you'd like any further help in preparing for a tournament, just send me a message.