Make sure you're on page one on Google search results
Adwords budgets are on average $5-10 per day and that's usually quite effective depending on competition. You only pay for the clicks which lead to your website or online store. How these site visits convert to leads, it's up to your website or store. How the leads convert to sales, it's up to your product or service. Conversion is king.
You've got several options
Search network (text ads in google search results)
Display network (ads on websites)
Shopping ads (photos & links to your product or service in google search results)