For long term black hat seo is not good for you and as per google it is not count as a good ranking technique.
Black hat seo reach you on first page of google search results very fast but after sometime google will block you.
For long term you should use white hat seo techniques, it takes time but very helpful and safe.
In search engine optimization (SEO) terminology, Black Hat SEO refers to the use of aggressive SEO strategies, techniques and tactics that focus only on search engines and not a human audience, and usually does not obey search engines rules.
Hey dear i know as far as stuffing of the keywords was once my favorite black hat SEO method that i have used many a times. It is the easiest way to get on the board and let the search engine know that what you want to achieve from it.