I'll confirm all of these replies so far. There are many variables and questions to be asked and answered, and might involve paid professional services to complete a more formal site survey. There are also tools that can assist if you have some of the expertise.
Cannot answer the question though except with a bunch of questions like is this greenfield or brownfield, what kind of venue is it, need to examine the floorplans and building materials, AP mounting & wiring options and location (like walls versus low or high ceilings), is the design for coverage or performance or some combination, what is the expected average versus max user density, what are the primary applications that will be running, does it need to support voice and/or location, what are the capabilities of the client devices (band, channel width, # streams, etc) among other things like what are your authentication mechanisms, are there specific performance criteria to design to, what are the plans to have different SSIDs for different use like internal vs guest, etc.
Sorry to ramble, there's a lot that goes into it, and the answer is always "it depends". PM me to discuss offline if you like.