I think it is great that you want to help, I agree that it says a lot about you. I would like to pass along the advice my father gave to me.
Five months ago I was forced out of my main occupation. My brother and I have had a part time landscaping business for five years and I decided this was my chance to try it full time.
In the past we shared the work, expenses and profits. Now there was to be a different formula - I would work more, use the equipment (that we purchased together) more, etc. I was unsure how to keep track of everything and make it fair for both of us.
Instead of telling me how split everything my dad told me this: Money can come between anyone. Money can come between a man and woman who share the same bed, money can come between life long friends and it can come between brothers, and the damage it can do is sometimes never undone.
My brother and I had a long talk one night in the woodshop and I told him I now wanted to make a living off what we had built together. At the end of the night we had filled in the blanks of how, when and how much. But most importantly, we agreed to speak up at the first moment either of us felt uneasy about the money situation. So far this is working well because we both know exactly what to expect from each other.
If you have never been in the lawn service business heed this: It is not easy money, but it can be good money. However, the guy on the seat who is sweating in 95-degree heat, running through spider webs with grass clipping stuck to every part of his body, while constantly being bitten by everything that bites will at some point ask himself "why am I doing this?" My answer to myself, while mowing 100+ acres a month, was that it paid some bills and would one day lead to something bigger and better - It has. 
I know this is a long thread and I am not sure if it helps at all but I hope it does. Good luck to you.