There are a number of things to consider before entering the sale process.
1) Is your company maximally positioned to get the best return/price, or are there things you need to do increase your chance of a sale, and your chance of the best price?
2) Is a sale to an external party the best option, or is there another option that's better? If to an external party, will this be to someone you work with (a client or vendor), a strategic partner, or a financial buyer/equity firm?
3) Do you intend to sell all of the company in one shot, or a portion of the company in order to finance more dynamic growth, selling the rest at an even higher price later?
Be clear on your goals and make sure you're ready before beginning the process. Once you start, you may find yourself in the awkward position of being asked to reveal previously confidential finances, strategic plans, etc., to people who you once considered clients or even competitors. It can be a nerve racking process.
Have you had a valuation done to determine a fair price for your company? Keep in mind there are many types of valuations for many purposes. Valuations to consider are financial (DCF) valuations by valuation specialists or accounting firms, as well as market-driven valuations that an investment banker would prepare. Financial valuations tell you what your firm is theoretically worth; market-driven valuations tell you what similar firm have sold for. They're different but valuable before you enter into a negotiation process.
As to your question of how the sale process works, the best sale process does not approach just one potential suitor. The disadvantages of approaching one potential suitor include 1) you're only hearing one plan for what's going to happen to what you've created, and 2) you're only hearing one offer. The best sales process creates an auction style environment that creates multiple bids for the company, driving up the returns for you and leaving you more confident that you're picking a good outcome for the company on which you've toiled so hard.
Let's talk about resources:
1) If you're determined to D.I.Y., then get educated. You've already started this by being here, but continue to read. Google. Reach out to me through LinkedIn. Check out Axial Network (Axial.net). It's a great place for business owners to go to transact. And check out our blog at http://meritharborgroup.com - it has great information about the selling process.
2) Consider Exit or Transition Planning. The purpose of this planning is to a) choose the right exit strategy that fits the business and the owners, and b) make sure the business and owners are ready for the exit and will get maximal returns. Remember that buyers like to discount for every problem they find in the business. Exit Planning is about fixing those problems and maximizing your return.
3) If you're serious about selling and want maximum returns, think about not doing it yourself. Hire an Investment Banker (or a business broker if your revenues are under $5M). They are skilled at running a process that will get you the best returns.
I hope this helps. Reach out to me for more.