Trying to get any TFS build definition to come pre-equipped with nuget restore so we can get the packages folder out of source control, but don't have a way to make sure these steps are at the beginning of every new build definition automatically. Any ideas?
You can't force it. You can encourage people to use templates (either the out-of-the-box templates or templates you create yourself), but you can't say "only allow users to create build definitions based on templates".