A training program’s effectiveness is going to be measured by how well its employees perform. If your employees are well-trained, your business will be more profitable.
The first important thing when designing an effective training program is to design the program to meet the needs of the business. If at all possible, the training materials should be proprietary. The program should be designed by the business for the needs of the business. If you just use generic materials, you might get some benefit out of them, but not as much as if they are designed to meet the needs of the business specifically.
Almost as important as the development of materials is having people who implement the training program. Who trains your new employees is important. If you have good people in charge of making sure that every new employee learns what to do and how to do it, you will be able to spend less time later on in making sure they do their jobs.
Finally, you should continue to evaluate the training program to ensure that it still meets your company's needs, and adapt it as required.