There are many ways to train dogs and I doubt that there will ever be a definitive answer as to which method is best. There's an old joke that sums it up quite well: "What's the one thing that 3 dog trainers will always agree on? That the other 2 trainers are doing it wrong."
So how is a person to know what to do? It is best to research the methods of trainers that you think you'd like to work with and then go and watch them work. If they won't let you do this, then you may want to keep looking. Not all methods are going to appeal to everyone and it will also depend on what level and type of training your are seeking.
Here is a list of what we consider to be Ingredients for Successful Training:
It is too confusing for your dog if you allow it to pull on the leash when heeling one day and not the next
Don't expect more from your dog than what it can do. If things start to deteriorate, get professional advice to figure out why, and start again.
Fun – There is no room for frustration
Encourage, motivate, and praise to get the most from your dog
Make it easy to understand
Keep it simple – one word commands are best combined with consistent leash and body techniques
Don't give a command that you can't enforce (use a leash) until the dog has a solid understanding of the exercise
Train regularly – be committed, but don't over train your dog
Twice daily for 30 minutes is great, but you can also break it down into shorter and more frequent sessions if that is too much for your dog
You must build a solid base of obedience before you can move onto intermediate, advanced, etc.
Never abuse your dog!
Have the proper equipment
Make sure you have the right tools for the training you are doing and that they are fitted correctly and you know how to use them
Always finish on a positive note
Even if you are having a less than perfect session, you must finish on a positive note so choose an exercise that is easy for your dog, praise when you get the desired results and end the lesson there
Your dog should have at least as much play time as training time
Take the time to play with your dog once your training session is over