First thing first. Rates. If you are looking to hire someone then, obviously, you have a budget planned out. Rates differ from photographer to photographer and so do the amount of pictures they can deliver. Thus the best option would be to hire the photographer who can deliver the most photos within a given amount of time at the cheapest rate. At the interview, ask the photographers how much their rates are and how many hours they are willing to work and also how many photos they can take in the hours they work. With this information, you can calculate the price of each picture and how many pictures the photographers can take in an hour. After having interviewed all possible candidates, the best bet to hire would be the photographer who can take a reasonable amount of pictures an hour at the best price.
You definitely want someone who has professional grade equipment. The equipment shouldn’t only be limited to just cameras and lenses. Your potential photographer should have lighting equipment, stands and basically anything which would help to capture perfect images. Make sure you read up on photography equipment so that you can properly assess the photographer’s knowledge on his equipment. Ask the photographers what equipment they have and relevant questions regarding the subject matter.
Ask to see the photographer’s portfolio if you haven’t seen it yet. A strong portfolio speaks for itself. You can judge whether your job is right for the potential product photographer.
Another important factor is whether the photographer will study up on your product before the shoot. If he does not have adequate knowledge regarding the product then chances are you might get unsatisfactory results if an art director is also not present. Basically you need to know whether your guy needs to be accompanied by an additional art director or not. So ask accordingly.
Lastly, you need to know whether your photographer can edit photos. You should tend to go towards photographers who can edit the photos if needed. Nothing over the top but some simple retouching and other stuff along those lines. Be sure to ask about their experiences with photo editing software.
If you follow these simple guidelines then congratulations, you should be able to hire the perfect photographer for the job!!