I think the most important thing is making your expectations clear--quality of work, productivity, customer relations, safety.
The best way to do this is have an "employee handbook". Big pain to put together the first time, then takes time to keep up to date.
The methods and quality of work can be based on the National Electrical Installation Standards (published by NECA). Productivity expectations can be based on the cost estimating books or your own man-hour figures for a specific kid of job. Safety is a biggie, as an employer, in the law's eye you are responsible for the employee's safety; this means that you have to tell the employee what safety practices they must use when they're working for you, and the consequences if they don't (warning, time off w/o pay, firing).
It'd be ideal if everyone was on the same wavelength on productivity, quality, and safety. If you're lucky, you'll find someone who is in sync with you. Then having all your expectations put down in writing seems like overkill. But some states require written safety procedures for any company with empolyees. You can buy packaged "safety handbooks" for general office setting, don't know if anyone has one for electrical contractong business.
It's easy to see why so many guys run one-man shows. Good to hear you're busy, best of luck finding a good worker or two.
p.s. One thing you can do to protect yourself is set a zero tolerance policy for drugs and alcohol on the job. CP