There are many things people should be aware of when hiring consultants for technical work.
First and the foremost, the most important thing about the technical consultant is their technical abilities of course. You shouldn’t have any doubt in your mind that the person can handle the job. Electrical and computer engineering is a vast field. There are many sub fields that fall under the general field of “electrical and computer engineering”, and nobody can be an expert in all of them. So the person’s background, education and experience should be taken into account to make sure they can handle your project. But, they do not have to be someone who has done something exactly like your project in the past. They just need to be someone with a background that prepares them for your project.