Assuming you have a website or you should at least have a page You’ll need to be seen by the engines.
SEO obviously means Search Engine Optimization. The search engines will put you in the light of traffic if you use the proper phrases according to your niche. I wrote this ad, so that you may have a better understanding.

SEO takes time.... and a very long time normally before you get some results. So you still need to consider paid search at the beginning of your business, or you won't get any income to sustain.