It really depends on how high tech you want to go with it...you can count calories online with Fitday or something similar, and basically have a log for each day. You can put in foods that you have the packaging for, etc. and if you don't, they have a list of foods that you can get estimates from.
If you don't want to count online, buy a small notebook tablet-the mini size. I do this, and use a page for each day, and just date the top. I travel a lot, so I don't have internet access when I do-and the tablet is easier because of that. You can buy a book at the bookstore which has calorie information, there is a foods list here at 3FC, and most large restaurants have information if you want the calories of their dishes before you go out to eat, to plan ahead.
Also, be sure that you space your calories out throughout the day-don't eat 100 calories for breakfast, and save the rest for a huge dinner.
Good luck!