Ask yourself, why someone would buy from you? What needs will it satisfy? How you can stand our from the crowd?
Do not try to become a jack of all trades and master of none. It will have real negative affect on your business growth.
Think from the customer perspective.
Selecting a niche is essential to success. e.g. If you want to start a freelancing carrier and quit your job. You should know the market where there is need for your skill and clients are willing to pay for quality products and you can provide them good quality contents. If you focus on all types of writing you will find it difficult to grow but by focus on your expertise and find projects you will build your path towards business success soon.