I would start with communications and awareness, both internally and externally. It's changing the way the government procures. It's a change program. You've got to get people to buy into what you're doing internally, because they're the people who are going to be delivering it on the ground.
You want your market outside to be fully aware of what you're doing. You need to be talking to the small business world to make sure that they understand what the government is aiming to achieve and that they are pushing from the outside and making it difficult not to comply.
A third thing, depending on where your government would be in its life cycle, would be something like mystery shopper, which enables you to understand the barriers as they are experienced by businesses on the ground, or perhaps focusing on bureaucracy. Governments love bureaucracy. Businesses don't.