When developing your leg program, there are a few things you should keep in mind. How you train is really going to dictate the types of results you get so you will need to make sure your leg program is geared towards your individual goal.
Firstly, if you are looking to gain as much mass as possible, you will want to focus in on the more compound lifts such as squats, deadlifts and lunges. These are going to work the largest number of muscle fibres and hence produce the greatest mass gains from your leg program. Couple that with enough rest and calories and new muscle tissue will be yours soon enough.
If your goal on the other hand is muscular definition, then you will need to reduce calories slightly in order to lose some body fat and do some compound lifts but then also include some isolation work to really bring out the definition. This would include things such as quad extensions, hamstring curls and one legged calf raises. You may also wish to get started on some higher intensity interval sprint work as this has been shown to be one of the most effective forms of cardio when it comes to reducing body fat.
Finally if you are actually looking to reduce the size of your lower body (some males who have bulked up no longer wish to carry as much muscle mass or alternatively some females just want to look thinner), then you should perform one or two resistance exercises with heavy weights but then focus more on performing longer duration cardio. This is an odd goal since it is geared more towards muscle breakdown than anything but it can be done if you are training correctly. Still lift heavy enough to try and retain some of your leg strength as this is important. When you couple that with more cardio work though it will inhibit further size gains so you won't have to worry size increases.
So consider these factors when you are developing your plan and make sure you are going about it in an effective manner.