I've found that customers respond much better when you position additional services as recommendations rather than upsells.
Instead of trying to sell them more, explain what you noticed and what options are available. That gives them the information without making them feel pressured.
For example, "While I was looking at this, I noticed. It's not something you have to do today, but it's something you may want to keep an eye on."
That approach builds trust because you're educating rather than selling. Ironically, customers are often more likely to buy when they don't feel like they're being sold to.
