There are 3 key ingredients for the successful (successful = profitable) vending machine business:
Going for existing routes for sale is a much better solution, than developing your own routes from zero. The option to purchase an established vending machine business is much simpler than doing everything yourself. If you decide to do the latter, that will provide you immediate source of income.
Buying locations is easy. Keeping them is hard! The only way to do so is by delivering outstanding customer service. That will take some time and will require some good business practices and a lot of dedication.
What does it mean to optimize your vending operations, though? Thinking about optimization it is all about identifying your biggest opportunity and taking advantage of it, so to bring a positive impact to your bottom line. Is it to say: optimization is revenue maximization.