When entrepreneurs look to sell their companies, it is astounding the types of mistakes they make.  An acquisition is both a time-honored, and increasing common, way of exiting a startup, so every entrepreneur should run their business with an acquisition in mind.  If you do, and an IPO comes your way, you'll still be in good shape

Here are some tips for being M&A ready when the times comes:

1) Keep meticulous financial records (quickbooks or QB online is quick, easy, cheap...use it!)
    a)  Have a good accountant and pay them every year at least to review your books and do your tax returns
2) Keep meticulous LEGAL records - read everything before you sign it so you know what you are committing to
    a) If you make board resolutions, write and have everyone sign a UWC - unanimous written consent of the board - then file it appropriately.  This should take about 30 minutes.  Don't try and backdate them later!  It's too easy for things to be forgotten, lost, or people to later regret decisions.  The discipline of real time UWC's protects you, the board and the company
3) Have absolute integrity in everything you do - then there will never be any questions
4) Use a payroll company to take care of all your payroll - their charges are cheap - in the $30-$60 /month range for a startup - they make their money on the tax float, but if you use a reputable firm, you can be assured that all your taxes (and there are LOTS of them) are filed on time!

What NOT to do
1) Be sloppy in how you run your business
2) Be unable to explain, or articulate, how your business runs
3) Have sloppy contracts and other legal records
4) Believe that you'll be able to backdate your UWC's or other board and legal authorizations "at some future time"
5) Have "approximate" financial records
6) "Do it yourself legal work" (see Lawyers - You REALLY need great legal counsel - and there are a handful of guys in town who 'get it')
7) Let the brokers massage the financials and then present them as "provided by the company"

In selling a business, there is the little league and the big league.  In the little league there are a slew of brokers who handle transactions into the couple million dollar range (they'd all like to handle much bigger ones, but their system breaks down).  Most of them have emerged from the real estate business - they don't have any financial background (or very little), and they are very commission driven.  Although there are good deals to be found in this low end (most businesses are being bought for up to 3 Times trailing cash flow), be prepared to be patient if you're a buyer and slog through a lot of stuff that is not "exactly as represented", poorly run, etc.   If you're a seller, be prepared that many buyers coming through this tranch of brokers is not very sophisticated and you may be somewhat disappointed in who comes to see your business.

If you want to navigate these waters - the best way is to find (usually through recommendation) a really good broker who will help search for you.  The listing broker typically gets 10% of the deal as commission, the "buyer's broker" (who brings the buyer) typically gets 10% of that, or 1% of the deal (a little strange as a system, IMO).  So a lot of people don't want to help the buyer - but there are some and it makes the process MUCH easier and more productive. Make sure you commit to reward that person for their help!