As you interview relatives and perform other genealogical research, you will find yourself accumulating small mountains of material! The best approach to take is to develop an organizing system early and stick to it, so you are never faced with the need to sort massive piles. If there's a folder that's the obvious home for a document when you find it, chances are it will make it into that folder. But if you just put it on the stack, it may remain there for months or even years, and you may even find yourself reordering the same document, just because you didn't realize you already had it buried in the piles that accent your home office.
If you are considering writing a family history, you will want to take this into account in developing your organizing system. There are numerous resources to help you create a system that works for you, so you don't need to invent everything from scratch. But bear in mind that the intention to write a family history - and the approach you decide to take - may affect how you collect and store your records.
For instance, in addition to individual, family, couple or place-oriented files, you may wish to create a chronological file. Perhaps as you obtain a new document, you will write up an index card for your chronological file and note where you stored the original in your other files. In this way, you will slowly build up a chronology to use as a basis of your family's history when you get the inspiration to start typing it up.
If you decide to use another approach - such as a theme based one focusing on topics like work, school, travel, food, and so forth - some sort of as-you-go, cross-referencing system would also be useful and save you a lot of digging through file folders when you get ready to write. Whichever organizing system you use, the gaps in your knowledge will quickly become apparent and help steer your future research efforts.