concordia

What country are you from?
There is no magic number, as stated above. However, your medial explanation is very confusing. Could THAT be the reason why you were denied? Without simple, straightforward explanations it is hard to give you a solid answer
good luck

There are no magic numbers of trips or any set in stone criteria for getting a tourist visa. Normally strong ties to your home country (employment, owning property, etc.) is the most important criteria, a good travel pattern to different countries will help, but just how much will depend on your other factors.