(Obviously there are some varying opinions on this subject, but through some information that I've gathered and from my own personal experience, I would like to share my input.)
** Is he/she certified? A personal trainer should have a current personal training certification as well as an up-to-date CPR & first aid certification.
** Does he/she have experience? An experienced trainer is ideal, however many trainers are young and may just be starting out in the field. If thats the case, keep an open mind, but make sure they are certified. I've met and interviewed several trainers who are currently in college studying kinesiology or exercise science.. That shows that they are serious and passionate about their field and obviously obtaining essential knowledge.
** Does this person understand my fitness goals? Look for someone who can relate to you and truly understand your goals. A good trainer should be able to customize a program according to your fitness level and goals.
** Does he/she know how to work around my physical limitations/injuries? A knowledgable trainer should know how to work around common injuries to prevent any further harm. If you have back problems, ask the trainer how he or she plans to work around that issue.
** Can this person motivate me? A trainer should motivate, not intimidate. Look for a trainer who can push you and uplift you. You will be spending A LOT of time with this person, make sure you like them and they make you feel comfortable.
** Is he/she fit? I wouldn't want to go to a dental hygienist who has bad teeth. Do you want to go to a trainer who isn't in shape? The answer is probably NO. Look for a trainer who practices what he/she preaches.
Bottom line... If you go in for a consultation with a potential trainer, don't be afraid to ask questions. The right qualified personal trainer can make all the difference in the world, but hiring an inexperienced/non-certified trainer is just plain dangerous. Make sure you do your research to choose the best fit for you!