Dear Sir, I am Doctor of Medicine and surgery, I am interested in writing in these topics, You all are masters of web and already in click bank business. In Which topic I should create my ebook, video tutorials. Acne Obesity Hemmoriods
All three of those are extremely competitive and saturated niches. If you're able to create an exceptional product which will convert very well, give it a shot. But this would require a lot of money for a copywriter, split testing, and other expenses. All 3 are tough niches, and there are several clickbank products for all of them. Maybe you can try making a product for a less-common medical problem .
You could try delving into a sub-niche within one of those niches. eg. how to get rid of acne scars, back acne, bumb acne, chest acne, hormonal acne, whiteheads, blackheads More specific and targeted, and most probably less competition. The guy who made facialsweat.com is a good example IMO. There are all these products on hyperhidrosis / excessive sweating fighting the same fight, and then you see this guy who comes up with facialsweat.com It addresses a very specific problem. And if you ask me, I think excessive sweating on the face is probably the most embarassing place you can have this problem. And no, it is not my site lol. Just giving an example. Well, good luck. I guess it's just a matter of thinking outside of the box and not limiting yourself.