which IM/LOA approach worked for you, how to find out which one is best for me?
 

There is so much literature out there - Abraham-Hicks, Science of Getting Rich, Think and Grow Rich, Silva Method - just to name a few that I have read or heard of. Steve also has his own spin on how to visualize and manifest as well. And you can find many other practices, such as affirmations, positive thinking, NLP.

From what I understand, the common principle is that your current vibrations (thoughts/feelings) has to be congruent with the state you will be in when your desire manifests. Want wealth? Visualize and feel as if you are already wealthy.

I guess I am feeling a bit overwhelmed with where to start. I have read many books on various related topics. I have had a couple of successes with affirmations and visualizations, but most of the time my desires have not worked out.

Hence the question: which approach has worked successfully for you? How do I know which approaches I should try out, and when to switch methods if things are manifesting?

I would say start with something that clicks with you. That is probably what will work best for you as well. Pretty simple advice, but I have found that LoA works best for me when I keep it simple. :)