The seven most expensive mistakes Starbucks customers make with their orders - and how you can get more bean for your buck

A former Starbucks barista revealed what customers should stop wasting their money on while visiting the coffeehouse chain.

Inga Parkel discussed seven spending mistakes with Business Insider this month, after working at Starbucks for a year.

Referring to herself as a 'stingy spender,' Parkel says she paid close attention to customers while she was working and noticed they would sometimes shell out more cash than they really needed to.

'I became extremely familiar with just how expensive the popular coffee chain is,' she said.

Parkel shared her tips to ensure customers save money and get what they want out of their Starbucks orders.

Don't pay a premium for cold drinks with little ice  

Customers ordering cold drinks have a simple option for getting more drink for their money.

The former barista told Business Insider that the key is to 'specify that you'd like light ice.'

'Baristas are aware that the oversize scoop of ice in a drink can be frustrating,' said Parkel. 

'But many are happy to replace the extra ice with liquid if you ask for it.'

The former barista added that the light ice option for drinks is available on the Starbucks app. 

Don't pay for a shot of vanilla syrup in a soy latte or cappuccino

The vanilla syrup shot in a plain Starbucks coffee drink could make it sweeter, but it is a small mistake that unnecessarily costs a customer money.

According to Parkel, the soy milk Starbucks uses is vanilla-flavored and 'more subtle' than a pump of syrup.

Parkel's solution is to order a sweetened coffee with soy milk instead of paying a fee for unsweetened oat milk or almond milk, or vanilla syrup.

Unfortunately, this solution will not work for customers who order drinks with one pump of caramel, hazelnut, or peppermint syrups. 

Join the rewards program

Regular Starbucks customers who purchase merchandise are making the mistake if they don't take advantage of the coffeehouse chain's rewards program.

To join Starbucks Rewards, customers must create an account online or on the app.

From there, they can score reward points every time they purchase something at Starbucks and redeem them for complimentary items.

'If you have 400 points, you can select any merchandise worth up to $20,' said Parkel.

If an item is more than $20, the customer would need to pay the difference, but it is still a money-saver.

Stop ordering Americanos

Americanos at Starbucks can be iced or hot, and ordering a grande that could cost around $4 is a pricey mistake.

Parkel described the Americano as a drink with 'three shots of espresso with water.'

The former barista suggested that customers who want to save money on an Americano order a customized drink instead.

'Ask for a doppio or triple shot of espresso (whatever you prefer) in a grande cup, and then ask for added water,' Parkel told Business Insider.

'You can essentially get an Americano for almost a dollar less.' 

Don't purchase hot venti lattes for a caffeine fix

One error that customers may not realize they're making is not realizing that cappuccinos and hot venti lattes only have two espresso shots.

Parkel pointed out that grande lattes have the same number of espresso shots as a venti.

'In a way, buying a venti latte means you're paying half a dollar more for a more diluted caffeine-to-coffee ratio,' she said.

She noted that this does not apply to iced lattes because a grande comes with two shots of espresso, and a venti has three.

Customers can optimize their money to caffeine ratio by ordering grande hot lattes rather than a venti.   

Take advantage of the 'bring your own cup' discount

Customers who don't take advantage of the coffeehouse chain's reusable cup program are leaving money on the table and missing out on an opportunity to help the environment. 

Starbucks customers can fix this error by bringing their own mugs into a participating location.

The program started on January 3 in the US and Canada. It allows customers to bring their clean, personal cups to any participating store for in-store, mobile, or drive-thru orders.

This would not only be the green choice, but it would save a customer 10 cents on their drink order.

Rewards members will also earn 25 bonus stars when using their own personal mug.

Stop purchasing bottled water

Starbucks sells Ethos bottled water at its locations for more than $2.45 - but there is another option that won't cost a cent.

The easy solution to save money on water is to request a cup of water in any size.

Customers can also request that baristas add ice to their water. 

'I can understand if you absolutely need something unopened, but other than that, there's no reason to pay full price for the one thing the chain offers for free,' said Parkel.