Don't let someone rip you off. You know how you will be at fast food restaurant and they will suggestive sell? Like ask if you want a cookie with that or a drink. They may be making sure they have the order right but it is also known as suggestive selling.
But restaurants aren't the only ones who do this. Mechanics also do this. They suggest that your air filter be replaced or your wipers etc. The air filter may actually need to be replaced but you don't know that. It may be just fine and they want some extra money out of you. So don't always say yes. Don't always trust them. Do your research on how often your air filter etc need to be replaced. And check your wiper blades before you get an oil change so you know what condition they are in. I use mine til they are just a rubber string on a stick.
Also doctors will do this too. Just an extra blood test and then another appointment to follow up and you go in and he says everything is fine. You just paid for a doctors appointment you didn't need. Do you research if you are sick. Eat healthy. It makes me so mad when they need more money and they suggest things that I don't need. If you have a problem ..you will know it. I only go to see the doc if I need a refill on my meds and THEN I take a blood test to make sure everything is okay. Then I won't have to go til another 6 months which is better than having to go every month for no reason.
Don't let these people take advantage of you. Most people can just ask their parents for advice. But we can't. And we can't keep being ripped off by idiots.