Hopefully, you will only need an attorney when you establish your business to consider the legal form it will take. An attorney will be able to advise you on the pros and cons of each type of legal form in more detail than what is included in this website. The attorney and can also prepare the documents or required filings although you will not necessarily need an attorney to do this (unless you need a partnership agreement). There are software packages with boilerplate templates that you can use. Additionally, if you're willing to spend the time on the telephone (or surfing the net), most states will answer questions about what forms to complete and how to complete them.
Having an attorney on retainer may give you additional peace of mind. A retainer is an arrangement where you pay a preset fee (monthly often) whether or not you use the service and the attorney agrees to be available for some predetermined amount of time to provide advice and perform services for you. Find out what a retainer arrangement would cost. It may be more feasible to speak with the attorney on an as-needed basis. You don't want to pay for a service you don't use.
Whichever route you take, find an attorney knowledgeable about commercial law and the consulting industry that you can call if you need to. A family attorney or criminal law specialist will not have the expertise to help you run your business.