It might seem like (something), but (sentence)

When someone is making a bad decision, you can use this phrase to change their mind. It means that their way of thinking is incorrect. For example:

It might seem like a waste of time at first, but as you continue to practice you'll see better and better results.

It might seem like you can make more money by quitting school and getting a job directly, but in the long run you'll end up earning a lot more money if you earn a degree.

(something) is no big deal

When you say that something is "no big deal" it means that it's not a problem. It's not important for you to worry about it.

A: I'm so, so sorry.

B: Don't worry about it. It's no big deal.

You can also use "no big deal" to say that something isn't important. For example, if someone asks you about an award you've won, you can humbly say:

Yeah, it's no big deal.

(something) reflects badly on (a person or organization)

When you do something bad, it makes people lose respect for you. It might also make people lose respect for people who are connected to you, like your parents, your boss, your coworkers, or even your entire country. To describe this, we say that your actions "reflect badly on ___":

Scandals like these reflect very badly on the current administration.

You're only thinking about yourself. Did you ever stop to consider that it reflects badly on us as well?

You can also say that an action "reflects well on" something. For example, the principal of a school might say this in a speech to the students:

We're here to do everything we can to help you achieve, because when you accomplish great things, that also reflects well on us.