what are the steps you follow to create a drug discovery, and principles.?

I don't understand your cross-question, but I'll try to answer what I think you're asking
First, settle on on a topic and read everything you can about it. I mingy EVERYTHING. Then you'll find something interesting to investigate about. I recommend pubmed.org for researching, a obedient source of biomedical papers.
Then, gather everything and opt exactly what is your question. Try to preserve it simple and straightforward. You can divide it in several little question. Control all the variables and brand name sure that the change you're expecting within your experiment can happen lately because of what you have done, not because anything else. Have a positive and denial control, that way you can know for sure what the results are. Then do the experiment and I hope you be right. If you weren't, well, immediately you can rule out that possibility and rephrase the question.
First, I would read everything more or less a subject.
Then take a significant amount of drugs. Then, surrounded by my inebriated state, my mind would dream up some discovery about that subject. And voila! Drug discovery at its finest.
Worked for Aerosmith.