What do you mean by "paid SEO" ?The best way to promote your small business is by doing SEO. First of all, you have to list your business website on google and rank it as you have to put it on no. locally. So for it, organic SEO will help you out. After it, you can go for paid SEO also to make your business on a larger scale by spending some more money. But in my opinion, the best way will be organic SEO.
Do you mean SEM? (Search Engine Marketing) ?