What are "Harvest and Outright"? How do you use them?
The question you are asking isn't as critical a question as you might think. Tables in one FileMaker Database File can be accessed from another FileMaker File so you can put all your tables in one file or several and the look and feel of your database system is much the same.
What you DON'T want to do is set up a system where you have to store the same data in more than one part of your system. You don't, for example, want to set up a table of contact information in one part of your system and then have a different table of contacts in another.
While there can be distinct advantages to using more then one file in certain cases, "newbies" are usually better off keeping all of their tables in one file as it is slightly simpler and easier to work with.
Keep in mind that you can "grow" your solution, adding more tables, layouts, etc to your basic solution--gradually phasing out the other applications that you currently use as create a workable system in FileMaker with which to replace it.