Accept the first offer you get.
As a dealmaker I frequently receive calls from sellers seeking advice who have been approached by a buyer or investor group. After the elation they might feel about a potentially quick and hopefully lucrative exit wears off, reality sets in, as they ponder questions such as 1) is this the best offer? 2) are there other buyers out there I should be talking to? 3) do I want to negotiate this on my own? 4) is now the right time for an exit? and others.
Unless we believe the offer is so richly valued that it would be laughable to others, and the buyer has a solid history of completing deals, our recommendation is to reach out to other buyers. Rarely will the delay kill the existing offer, and almost universally you can improve the ultimate deal value, either through a better offer from a third party, or by improving the offer of the initial bidder. Working with one buyer limits your negotiating leverage and probably reduces your companys potential value. Following a disciplined go to market strategy is best for your company. It gives you the chance to involve many potential buyers, gauge the real market value of your company, and negotiate to get the best terms.