Best way to become a fitness/personal trainer ?

Since it is country specific I can't really answer your question.
I have however read online some complaints about how not all ways of getting certified give you the actual knowledge to properly train someone.

Maybe you could look for a good PT in your area, get some advice on how to get certified (if no PTs answer here) and perhaps do a small aprentenship with that PT so you get some actual experience.

I've looked into this recently, and it's pretty overwhelming to see so many certifications. Here are a couple of suggestions/tips that I have come to appreciate as it determines which avenue to explore.

1) If you plan on doing personal training at local gyms, find out from them if they have any specific certifications that they prefer or mandate. It would stink if you spend time/money becoming ACE certified, but the gyms around you prefer NASM or NSCA.

2) Consider taking a few anatomy/physiology/kinesiology classes at a local (or online) community college, especially if they offer a 2 year or 6-8 course certification in something along those lines. The PT certification is so people will hire you (for insurance purposes), but taking classes at a local school will give you more knowledge and that will help promote trust and expertise. When you hear about good and bad personal trainers, it often comes down to which of those got the PT certification and that's it versus those who got the PT certification and was educated in it as well.

IMO a certification is the final step in ones development, not the first step. I personally would never hire someone who didn't have a degree in exercise science along with experience, but most of the world isn't as picky. That being said, I believe that some type of more structured academic preparation is necessary. At a minimum I would recommend the ACSM resource guide for either personal training or the health/fitness specialist and the NSCA essentials for personal training. Go through each book cover to cover. While you are doing that I would also try to find some opportunities to actually do some training--either working with some friends or maybe shadowing a trainer.

http://www.nasm.org/how-to-become-a-personal-trainer

http://www.acefitness.org/fitness-certifications/personal-trainer-certification/how-to-become-a-personal-trainer.aspx

http://certification.acsm.org/acsm-certified-personal-trainer

read these over, then let us know which questions specifically you have.

Forget college. Get experience. I'm almost done with my Exercise Science degree and I didn't learn much about how I am going to transform someone's physique. The most I learned was when working on completing my associate's degree. I took a class that was going to prepare me for NASM and the teacher was pretty awesome. We didn't see eye to eye in a lot of things (training philosophies, etc) but overall he knew what he was talking.

If you want to make a good living as a personal trainer, you need to be extremely passionate about it and think about doing your own thing (opening up your own facility, creating a blog, ebook, etc). I know nurses make good money, a lot more than the average personal trainer since trainers only get paid when they have clients. If you become a great personal trainer and know how to market yourself and stand out from the rest, you'll do well. Work for a gym only for the experience but unless the gym is crazy busy with a ton of clients lining up for personal training (which is rarely the case except for gyms that are in rich communities), you are better off doing your own thing in the long run.

Good luck!