Start an organizational system early, and stick with it!
Create a file (both digital and hard-copy) for each school.
Make a spreadsheet for prerequisites: required and recommended courses.
Fill it in with schools you may be interested in.
Search for commonalities, and plan your schedule and schools from there.
Bookmark important websites.
Maintain a calendar.
Work on application materials ahead of time!
Take notes on each school you visit.
Admissions requirements, academic and financial information, general thoughts/impressions, etc.
Record your practical experience hours religiously! Some schools, especially vet and physical therapy schools, require a large number of practical experience hours. It will save you headaches during the application process if you record all of your hours along the way.
Reasons organization is so important
You don't want to miss a deadline or apply to a school you don't know enough about.
Applications are a huge investment of time and money. Organization helps ensure that your resources are being put to their best use.
Being organized will help make your life easier during hectic application time, when your schoolwork will inevitably pick up.