Idea: Think about non-family eyes on your genealogy
Institutions usually won't accept a stack of loose papers in haphazard order, like the mess I inherited, as shown at top! Unless a non-family member can make sense of your genealogy paperwork, it will not be useful to anyone.
The point of donating your documents is to help other researchers interested in any of your ancestors or that place or period in history. You may have an unusual set of records in your collection, or a person you've confirmed and documented in your family tree who is not mentioned on other trees, or a photo that connects your family to a certain time/location/event.
In general, the goal is to organize your genealogy documents so that non-family eyes can understand what's in the collection. Take inventory. Know what you have and figure out a logical way to put your materials in order--by surname or by family group, for instance. Family Search has good ideas here about organizing your files.
Neatness counts. You want your collection to be orderly and organized, without physically changing the materials. No punching holes in documents to insert into binders. No stapling, no rubber bands, no paper clips.
Idea: Written family tree, sources, and table of contents
You can guide outsiders through your family history by creating or adding detail to a written family tree or chart explaining who's who.
The Family Search wiki lists many sources of downloadable charts you can use, and you can also download from the National Archives. If you use genealogy software, you can generate reports. Or you may prefer to create a spreadsheet or use another system, as long as it's understandable by non-family eyes.
Cite your sources to show how you know what you know. Other researchers will appreciate seeing sources in writing. Again, neatness counts. So does accuracy. Double-check your spelling, dates, place names, and sources.
Consider a table of contents for each binder or box or file folder (and label binders and boxes and folders with your trusty label maker). You might assemble all tables of contents into a package that goes with your written family tree, to guide outside eyes through the collection.
Please don't leave behind a mess like the one I inherited. Little by little, start now to organize your genealogy collection and get it into shape for non-family eyes to understand.
For additional ideas about sorting your collection and writing instructions for its future, please also see my affordable best-selling genealogy book, Planning a Future for Your Family's Past.