How to learn to make a meaningful study without having an academical background? I am an autist who had been in therapie for 8 years. In that therapie I learned a lot about my own and later about others psychology. I also developed over the years an tendency to just experiment with my own and others perception of situations/interactions and evaluating the differences/similarity of different people's reaction. The amount of information I was able to gain and by that learn from it made me become kind of an experimenter by heart what started taking over to all aspects of my life.

Very often, I had already an idea of doing an experiment I should document because it might be interesting (but not meaningful) for others aswell, but I decided not to, as I had no idea how to do it.

Now through all the therapies I had and especially in group therapies, I figured a really big problem in getting an autism diagnosis is that the criteria for the diagnose are kinda subjective and many therapists hesitate to give it, as its hard for them to give a final judgement if someone has autism or not. I have an idea how this process could be improved by giving the therapists additional backup, so they could make a decision with more certainty and hence reduce the hesitation in the process of giving an autism diagnosis. I talked already with my therapist about my idea and he agreed that the idea sounds very interesting but that he knows from his field, that there are so many different opinions on what are the important criteria for an autism diagnosis, that my idea couldn't be generally applied due to the fact that it had to be individually phrased for anyone to find acceptance.

After that conversation I couldn't anymore let go the idea of making a study proofing that my idea would work. So far, I have an aim with that study, which would be improving the required time and precision of spotting the presence or absence of the criteria required for making an autism diagnosis.
I have a concept of how my idea could universally be applied in form of a questionnaire (despite I haven't considered yet, what questions had to be asked in specific). And I have an vague idea of how to design an experiment that possibly would proof (or disprove) the premise of my idea.

What from my understanding should be enough to (dis)proof a concept.

Now the only thing that prevents me from doing this study is, I have no idea how to perform such a study in a way that it has any means. I don't know how to check what related research others had already done or if someone made this study already before I did. I have no idea how to figure whats the threshold of candidates to participate in my study had to be, so the result is meaningful. I have no idea how to avoid or spot irregularitys in the results of the study. And I have no idea how to actually reach out to possible candidates wanting to participate in that study. As the around 30 other autists I know from which I could be lucky if half of them was interested to participate, I suspect by far wouldn't be enough for getting an meaningful result.

tl&amp;dr

So my question is, if I have no academical background and don't know how to design a study in its detail, how could I learn or find help for doing so outside of academia?
Given the comments of yourself and others here, let me make an orthogonal suggestion. Instead of exploring this on your own, you might try to contact someone in either medicine or psychology at a university or research center and speak to them about your ideas. You might provide a useful resource to someone who might be interested in following up your ideas, perhaps by guiding a student already under their guidance. 

But alternatively, your conversation might reveal to you that what you propose has already be well researched. Such a professional contact could, perhaps, point you to the answers you seek. 

This would result in minimal impact on your career, and might provide an interesting research problem to someone. 

Personal contact via an office visit is probably the best and most efficient way to get such a conversation started. An email might be ignored. Your therapist might be able to point you to a researcher.