Contributor: Transactional Attorney
Before discussing the business with potential buyers at all have them sign a Non-Disclosure Agreement ("NDA"). An NDA requires them to agree that they won't release any of the information you provide them regarding the business. An NDA is standard practice in any business transaction and you should be wary of any buyer who is unwilling to sign one.
Once the NDA is signed, you'll still want to get core financial and background information before releasing any information on your side. I would advise obtaining a personal financial statement from the principal buyer(s) as well as a business financial statement if they're buying your business under their company name.
It can also be helpful to obtain some key information as to their business purchase status and resources:
What types of businesses are they considering?
How long have they been looking?
How many other businesses have they evaluated?
Have they made any other offers? If not, why haven't they made an offer on another business? If so, why didn't the sale go through?
How much cash do they have for the purchase and for working capital?
Are they planning on obtaining financing? If so, from where, and for what percentage of the purchase price?
What collateral do they plan to use for any financing?
What is their business / employment background, and do they have any experience in your industry?
Depending on the buyer you may want to ask these questions informally in a phone call or email or you may prefer to prepare a more formal buyer questionnaire.
While there are not specific right or wrong answers, the responses should allow you to get a good sense early on who is serious and who isn't.
Disclosing information before you've entered into formal due diligence is a balancing act. On the one hand it's important to provide enough information to a potential buyer to make an educated decision to begin the due diligence process. On the other hand, you don't want to spend time and effort pulling together or revealing too much if a buyer is not serious.
You mentioned that you are taking calls and emails yourself. Selling your business is likely to be one of the largest transactions you'll undertake in your lifetime. If you're uncertain about the sale of your business at any stage, you may want to consider working with an experienced broker or advisor who will understand the proper balance between disclosure and discretion and can help guide you through the transaction from start to finish.