Se a business law attorney in your locale. Take any paperwork, such things as employee handbook, non-compete agreement. Be careful not to carry off customer lists and company documents. BUT, before you make a move, see an attorney. The process is not all that complicated, but there are pitfalls.
We do not have a client/attorney relationship until you make an appointment, we discuss your case face to face, I accept a retainer, and we explictly agree to enter into representation.
Well, to be 100% sure, don't violate any of the terms of the noncompete, if you signed one. In any event, don't use any trade secrets, customer lists, and confidential information belonging to your former (?) employer.
If you are putting any serious money in this project, and or are concerned enough to ask the question, you really should consult with an attorney. An attorney can help you identify the likelihood of an action on the part of your employer, what, in your specific situation, represents the most likely problem areas, what you might tweak to avoid or minimize your risks, etcetera.
With the level of detail you'd need to disclose, you probably don't want to post it here in a public forum. Good luck!
It is impossible to be free from being sued, but you can reduce the likelihood by understanding your legal rights and your contractual responsibilities to you previous employer. The trouble is that you don’t provide enough information to give even a perfunctory review of your company or your employment situation. Are you talking about non-compete clause, patent or copywriter infringement, use of customer lists, etc.?
All I can recommend is to confer with an attorney who has copies of both your business plan and your employment contract.
This is not legal advice and is not intended to create an attorney-client relationship. You should speak to an attorney for further information.