Main concern is should the money transaction take place after or before a service is done.
For example, painting the exterior of a house, interior, one room or full house, lawn care service, etc.

Or will it just be best to write up a contract for each customer stating money up front and look into some laws and regulations to support my structure?

I have no idea where you are but in my area the customary procedure on a large job is 1/3 at signing of contract, 1/3 at start of job, 1/3 at completion.

For smaller jobs (for example, mowing the lawn), I pay annually, by contract.