It **depends** on the Freelancing service you provide. If you are doing something that would go viral then you need to invest in Twitter/FB/Google Adwords because something that can go viral should catch the eye of as much people as possible and in this way you would have a strong network as well.

If you are freelancing locally or something, like teaching, you can get cheap pamphlets done and distribute them.

**Depending** on the Freelancing thing you do, you can invest **from advertisement to simply printing business cards.** 

It is just about finding what your business/freelancing model **lacks** at present. There is no general answer to this.