1. Always ask the videographer, what equipment provided in the quote and how many hours or days it needs to be rented. (tip: you don't always need 4K, because every smart phone can shoot in this resolution nowadays. It is way more important to have a bigger sensor or a higher sensor sensitivity, a high quality lens, or obviously the talent itself.).
2. The equipment they use is a real video camcorder or a fancy "DSLR"? True, these less expensive devices, now can be seen everywhere and even the middle range productions use them more and more. They are OK, but need to know when and how to use them.
3. Always ask if the team has any official certificate to do the work they do. For example enough a wrong frame rate or shutter speed to create videos, that needs to be reshot.
4. If there is any other employee, do they have the knowledge? Do they improve their skills anyhow? Are they part of any union or non union groups?
5. Who is going to take care of recordig a good sound? Are they bringing in another professional to do that?
6. Also it is advisable to ask if there were any productions where something went wrong. What happened in this case, how did they solve the issue?
7. If someone is really cheap you can start to worry. It is up to you to take that chance.
8. Is there any gurantee if the product is not good as they hoped for?
9. Do they have an insurance? Do they have the necessary papers to sign with all the people, location staff, etc?
10. Who is going to own the rights to the finished project?
11. Where can you use the video? Online, TV, anywhere? Some might ask 10 times more if it gets brodcast in TV.
12. Are they using legal softwares or just pirated stuff? Only professionals pay these high monthly prices. Even the background music used in the video should be copyright free, so you have piece of mind.
13. Time is money, but there is no company that charges for the first meeting. Actually yes, unfortunately there are some companies who will bill you. Do not expect to select the right candidate from an email offer. Meet them and ask all these questions.
14. Is the editing, rendering and uploading included in the given price? Some might leave it out and tells you later.
15. Archiving. Who is going to keep the finished project files? How long? Do they provide yoi the project files? Is there any backup in the worfklow?

Of course we could create another 100 points, but it is up to you how deep you want to learn about this business. Our advice is to be wise and spend some time getting familiar with some video terms. I hope we gave you some brief hints...