I know of two effective and sufficient methods - you will find others.

"It is a very effective method to create fear among the people," he said.

The most effective method so far was one that had not yet been used.

I need to know the most effective method to close it.

So he had applied another and much more effective method.

"I've found that the most effective method is to follow the lead of the children," she said.

This is considered the most effective method, though the least practical.

Living out an example is the most effective method of prevention.

What is the most effective method of dealing with this problem?

I don't think hitting children is a very effective method of teaching them anything.