Well, first of all, best of luck to you on your journey to great health and fitness!
Regarding getting a Trainer there are a few key elements behind ensuring you get the best experience.
1) The trainer is up to date with all their qualifications etc. In the U.K, we have a Register of Exercise Professionals in which all trainers must be a member and also keep up to date with 25 REPS points per year. Not sure what the process is if you are U.S.A side??? However, very important that you get a trainer that is current, as training approaches have advanced a lot in the last 5 years.
2) Great people skills - This may sound like the obvious, but it is so important that you get along with your trainer. He/she is going to inspire you to a better life! Wow, that's a big ask, not that you have to become their best friend, but you do need the basics of "I like, respect this person."
3) Passion, passion and more passion. The absolute priority behind your trainer. If they are passionate, it will inspire you to be passionate about your body and your success! It's easy to be passionate in the early days all by yourself, but after time wears on, you never know how that passion is going to last..... Have someone that gets you going "yes, I can do this!"
Finally, remember, you want a complete approach to health and wellness. All the pieces of the puzzle are going to need to be there for you if you want to get the most out of your lifestyle. Nutrition, exercise, motivation, emotional strength, it all add's up.
Great point that you were saying about you want to able to eventually workout your own programme's etc...... You MUST BECOME THE EXPERT FOR YOUR BODY!!!!! It's so true, when I have trained people I always have told them, if you are with me for more than six months then I am not doing my job correctly, I want to pass all my knowledge onto you so you can be your own motivator, PT and inspiration!
Hope this helps, any other questions, do not hezitate to ask.
To your success and wellness,
Pete