Personal trainers who work for a business tend to make an average wage, but if you're looking to freelance then there are several factors that can affect your income.
First of all - your skill level. Simply put, the better you are, the more you know, the more you can charge and people will pay for top of the line training..
Second - your marketing skills. You can be the best trainer in the world, and, while word of mouth does travel fast, it isn't the best form of advertising. You need to be prepared to get your name out there. Learning how to market yourself, get your name on the radio, the internet, in the newspapers, etc. If you can, write a book - an eBook, even, and give it away for free.
Third - customer satisfaction. So, you have your name out there and people are flocking to you, but you're so overloaded now that you can't give each person the full attention they deserve. Bad business. Make sure that you can give each and every customer the best possible service and they will keep coming back, often, with their friends and family.
It depends . Few more details will help to answer in length .
yes. depends on what your talking about also though