One of the most difficult thing about parenting is giving consequences. After all, your children may respond completely differently when given the same consequence. What is effective with one child may not be effective with another. How do you know which response is best? I don't believe that there's a good direct answer to this question but I can give you a little advice that may help. Many times, we think of people as being strict (tough) or loose (tender). Instead of being one or the other, my suggestion is to be both.
When you need to provide discipline, examine the behavior and ask yourself whether it would be beneficial to respond in a way that is tough or tender. By varying your response, you're likely to be more respected by your child and also respond in a way that is most appropriate for the behavior that you're trying to address.