Do you ask straight about their budget?
Do you mention your hourly rate from the start?
The point is to assess the financial benefit you would achieve without wasting time on discussions like project requirements, scope etc.
The first priority is to get them on the hook. Sell them on what you can do.
Then get a picture of who they are as a company and about the scope of the project. This gives you a sense of the budget.
Then talk money. What are their expectations? Are expectations in line with budget?