I’m 18 and want to start a business. I’m serious about this and am willing to invest all of my time. Does anyone have any suggestions?

I'm 13 btw you are a poopy stinky butthole

Poop.  LOL POOOOOOOOOOOOOOP!

First, go to school and get an MBA so you will understand how to run a business. 

how about a dog walker business after all it cost nothing .

It depends on what you're passionate about. If you like selling stuff, you could do some commerce. If you enjoy high tech, you could invest in the development of a cool solution, say, social media or something else. You could find the details here https://agilie.com/en/blog/why-you-should-consider...

what are you good at???

Does the area where you live have a MARKET for the goods or services you want to sell?

How much money do you have to get this thing off the ground?

ask yourself these questions.

You should start by getting a job in the field you want to start a business in. The best way to learn is to work for someone else. Once you get some experience in the industry, then you can start a business. You wouldn’t want to open a restaurant if you’ve never worked in one. It’s important to know and understand the industry before you risk your money and credit on it. At 18 you probably think you know everything already, but trust me there’s a lot to learn. College might also be a good idea.

If you need to ask strangers on a Forum like this what sort of business to set up, then you are FAR from ready to set up on your own.

Get a job, work for an employer for ten years in the field you are interested in, and THEN consider going it alone.

At 18 you do not have a lot of experience, and probably not the money to buy a franchise.  Best to start with something that you are familiar with.  What sort of work have you done ?  What does your dad and mom do that you might be familiar with?

TAKE SOME COURSES IN  RUNNING A BUSINESS, OR AT LEAST READ SOME BOOKS ABOUT IT. THEN GO EARN SOME WORKING CAPITAL. Four out of five business start-ups fail due to lack of knowledge, planning and funding.