There are some excellent web sites that have calorie counters, food journals, etc
to keep track of what you eat, or you can go
to the book store and
buy a simple calorie counter. Whether you do it online or buy a book, you will learn what size a portion is and how many calories/portion. Do make sure you keep a food journal so you know where your calories are coming from.
Try to drink plenty of water and do get plenty of rest.
Exercise: the idea of a pedometer is a great one.