We begin our M&A model by plugging into the spreadsheet some basic market data and corporate information about the target ("TargetCo") and acquirer ("BuyerCo"). Market data can be obtained from a number of sources, including FactSet, CapitalIQ, Google Finance, Reuters, and Bloomberg. Most corporate information can be found in SEC filings available online at the EDGAR database. Some things to keep in mind:

sample options table
Sample options table taken from Intel's 2008 10-K.

Note that we have specified which analyst research reports we are using for financial projections. When selecting a single research report, be sure that its key estimates (e.g. sales, EBITDA, EBIT, etc.) track consistently with Wall Street consensus and that ample detail 2-3 years forward is provided. Using individual research reports–rather than consensus–and citing your sources makes it easy for others to check your work.

It is good practice to color-code cells in your spreadsheet. In general, inputs are colored blue, calculated cells are colored black, and cells that link to other worksheets are colored green. Red may be used to identify cells that require special attention, but are not used to denote negative numbers.

Have a look at the current share price cells and you'll notice that we named them "acq_price" and "tgt_price". Naming cells is a good practice that allows us to more quickly reference them when building other worksheets in our model, and lets users know, at a glance, which cells an equation references. Open Excel's Define Name dialog box (Alt>i>n>d) to define names for cells that are used frequently throughout your model.