I believe visualization should be on the list. After all, seeing oneself in the desired situation or with the desired thing is part of instilling a strong belief, and some believe it actually conveys what you want to your subconscious and perhaps even to a higher power.

The most important element in manifestation, in my opinion, and from my experience is the emotional aspect. Without that, the other steps fall short, and without it, the other steps will not even work!

I, too, would agree that emotion or 'feeling good' is the most important one. We can wish for something but if we don't 'feel good' about it then I don't think we really believe that it's coming and if we do 'feel good' about the desire, we are not going to entertain any negative or conflicting thoughts on the subject.

I don't think there's really an order as everything fits together, but for the sake of clarity:

1. Getting clear about what you want and releasing any conflicting or negative beliefs
2. A strong desire towards what you want
3. A strong belief in and assumption that what you want to attain will definitely materialize
4. Feeling good about knowing that your manifestation will come about
5. Imagining or visualizing the end result of already having it, while feeling good
6. Relaxing and enjoying your life, knowing that the object of your desire is on its way to you
7. Taking inspired action at the appropriate time

Any doubt will seriously impede your progress or render your efforts worthless.

Any successful conscious manifestation is really a self fulfilling prophesy...

Without clarity nothing will happen.
Without desire there is no movement.
Without belief nothing is possible.
Without imagination no change is possible.
Without taking inspired action, you may miss the window of opportunity.

Furthermore, being happy and always feeling good now will net you all good things, even things you didn't know you wanted, but are more than happy to receive 8-)

What you have listed relates to Step 1 and 3 of the manifestation process which is described in my answer to this question.

So, logically, I would say that without Step 1, manifestation cannot happen. Therefore, launching the desire is the most important step as without it, none of the other steps can happen. Now, if you are talking about Step 3, having a dominant "feeling good" vibration is the key to getting what you want.

I think "feeling good" is the most important part too.

At number 5 I would put "inspired action" (that dream car will not appear in the garage until you go and buy it.... Or will it?)

I would add the word passion to the above list. Because you need to be passionate about what you want, and need; and you need to focus and concentrate your passion on your desire to manifest the outcome of your wish.

Is it just me or does it appear to others that all these words & concepts are describing the energy of love in all its forms of manifestation?