I have a job in retail selling high end home fitness equipment. What can I write off if I keep receipts??
General purchases like lunch, office supplies, etc.... What can be written off given my line of work?

If you work in a set location, like a store/storefront, do little customer entertaining and don't already itemize your taxes, not much.

Driving to and from work, and eating your own lunch, are not expensible on your taxes. Driving to a customers, taking a customer out to lunch, and buying office supplies may be.

But in order to claim the expenses you have to have enough expenses to "beat" the standard deduction given to everyone.

Save your receipts and see a tax professional in the spring.

Which type of fitness equipment would be most suitable for me? i am a 24yr.old mom?
my average weight for the past 7 or more yrs. has been 105-110 lbs.Since the last 8 mths. i have been gaining weight;especially my stomach,and arms,and thighs.I also have lots of leg pain especially around my knees.Also because of getting an Epidural for giving birth to two kids i get backpain or backstrain a lot.so i'd love to know what machine is most suitable for my needs.

The best advise is use the brain. You have to have the mind set and the will power. Set your mine to what you want and the rest will come easy. The mind is the best tool for losing weight. Think about everything you eat and think about doing different things to burn off the fat. Start out walking either in a park or a treadmill. Once you start that and have will power you will find other things to do. Look at pictures of how you were each day to inspire you. Without the will to put forth the effort you will be wasting your time. staying in shape is 80% in the mind. Your body will only do what your brain tells it to.

What equipment do i need to start a fitness center and equipment?

You need a place, a space you usually have to rent or buy.
You need showers, toilets, sinks, lockers.
You need treadmills, stair-steppers, weight sets, weight machines.
You need a counter and a cash register. You need carpet and mirrors. A sauna, hot tub and pool are nice. You need chairs and a scale for people to weight themselves. Raquetball courts are common. a running track is nice. basketball courts are good