If you are still in doubt as to how you will know who the right designer for your brand is, you can ask the following questions:
Work samples are like a resume or a CV. You need to judge and see for yourself how good the designer's work is based on his previous work samples. This way, you will get an idea of how he designs logos and what you can expect from him if you hire him to design your logo. Having enough work samples also proves that he is experienced in his field.
You can judge how good a designer is by seeing what questions he asks you. A designer will obviously want to know about your company, and he will prepare some questions and get answers to them by asking you. If he digs deeper about your company, you can tell that he wants to do his best to design a logo that will suit your company in every way possible. Whereas if he is mostly focused on what you want only, he will not design as good a logo to represent your company as he would have, he knows more about it.
It is obviously important to know the price before you accept the service. And using these previous questions, you can determine whether the service that will be offered to you is worth it for that price or not. Keep in mind that you are not just paying for the logo rather you are paying for their time, effort and probably also for the feedback of other experts on that logo design as designers may design separately but like to take feedback every now and then.
You shouldn't just ask the price and decide whether you want to hire that particular designer or not, you should also make sure to ask what else is included in the package besides the final deliverables for the logo design. Most designers also include charges for any additional deliverables that they will provide like stationary and printed T-shirts and mugs, etc. You should be sure to ask whether, if they are delivering these additional items, they have told you the complete cost along with the cost of those items or if they have yet to add the cost.
Getting a rough idea of when the logo design will be delivered to you is important as you will have to update your company in terms of printing new business cards, updating your company logo and possibly even making changes in the working of your company. So, you must know the amount of time it will take by the designer to finish your project. You will obviously not get an exact date of when it will be finished but a rough idea, you can work with.
It is important to know the design process so you will know if the designer will need a feedback from you and your co-workers or if you will only be shown the final product and some revisions will be done later on. You will also know how the designer is going to work on your logo and if he will be taking feedback from any other expert designers or not.
Unless it's a freelance designer, you will not be in contact with the designer directly. Most times, you will be in contact with a project manager that will oversee the work of the logo designer and update you and send your wishes or needs to him. This is also necessary to know as only then can you know who to stay in touch with during the logo design process. Any concerns or questions, you or the designer might have regarding the logo design, you can contact each other through that project manager.