What is the best view to sculpt in? Is it in the persective or orthographic view I tried sculpting a human head and according to the tutorials I watched, they normally sculpt in orthographic view and so I did so and in orthographic mode, my head models actually look good but once I switch to perspective mode then the model looks terrible, nothing is in the right proportion. I also tried exporting it to Unity in order to find out if it's only in Blender and in unity my model still looks weird.

I then tried to model in perspective mode and in that mode its extremely hard to sculpt so I want to know which mode is the right one to sculpt in so that I can continue sculpting.
There isn't necessarily a "correct" view to do anything in in blender.

However, know that in almost all cases, perspective view will be the view you will be viewing your model in afterwards, and is the physically correct way that people view the world. 

Orthographic mode is really useful, especially if you want to be able to compare distances and look at a model directly from the side, but I don't usually need to do that in sculpting, so I would recommend perspective view.

If you could elaborate a little more on what you mean by "extremely hard to sculpt", I might be able to provide better advice.