Lawyer assistance with the legal documents needed for operating private business

I run a business of training & coaching services.

1. What legalities do I need to know to keep myself & my business protected?

2. What do I include in my contract/agreement with my clients? I have two clientele bases, one solo business owners/startups and second, I work with companies as an executive coach & trainer.

3. How can I get help from a lawyer to put down a contract with all the legalities?