Running: When you meet with him ask him what his plans are for helping you meet your fatloss goal. I hear you when you say you want to weigh within a certain range, but perhaps bodyfat percentage might also be something you want to measure and is he able to do that for you?
Depending upon how he outlines his plan for you it may be possible to decide right then and there if he knows what he's talking about. Maybe. LOL.
Also, ask him about his certifications, how long has he been training clients, what type of additional continuing education courses he has taken. (These are required after you actually pass your cert to become a trainer. Most often these CEU's allow trainers to specialize or expand their knowledge in other areas such as working with a special population, or learning how to use the newest toys such as the TRX or balance and stability training. etc)
I would also have a list...oh yes, a list of some of the things you would like to learn or for your training sessions to include.
He may or may not be a good trainer. In my experience not all my trainers were created equal even with the same certs and degrees. Experience, how much time invested in researching, and how they balance their own life with fitness can make or break a trainer. However, you do take a little from everyone and mold it into your own.
Good luck! I hope it turns out to be a good experience. If not...you just move on.Eventually you will find someone who rocks and you follow them everywhere!
Kind of like your favorite hairdresser.