There's power in specializing. Like a neurosurgeon will outearn a general doctor every time - a contractor specializing in a few services will outperform his competitors. It makes your processes more predictable, hiring easier, and fulfillment certain.
If you're having trouble choosing three services, think back to last year. What services did you perform most of, which ones did you enjoy, and which ones generated the most profit for your business? You don't need to fill in each service. For example, if you only do bathroom remodeling, just fill in the first field.