Doing SEO for SMEs is no different that doing SEO for an enterprise site. However, the way in which we structure the agency SEO contract and the speed at which things are implemented are very different.
SME is a small to medium enterprise, and by definition being 'small' means we need to focus on building authority into your site. So, building in trust signals like links from mainstream media publications and getting your business understood as an 'entity' in Google's knowledge graph is essential.
The way in which SEO contracts are structured needs to be different. As a small business, you need flexibility and no lock in so you can dip your toe and progressively invest more over time as you see a return from your SEO work.
You also need a 'full service approach'. Typically in a small business, you don't have a marketing manager and a team of 10 people focused on writing copy, running PR, making content, promoting you on social,etc. It's usually one or two people running the marketing and in some cases it's the business owner themselves wearing multiple hats.
With that in mind, the agency needs to do everything and they need to do it fast as every penny in a SME's budget needs to count.