It would be very difficult for me to explain my "system" but suffice it to say it works for me and I have 4 plastic shoebox-like boxes with my 3x5 recipe cards filed according to appropriate food categories. Example: appetizers, breads, cakes, cookies, fish/seafood, etc. You get the idea. I have it divided and subdivided into about 53 categories. I have a separate category for cheesecake (love the stuff) as well as meatloaf. My fish/seafood section is broken down into various kinds of same.
I don't know how many recipes are in those 4 boxes, but I've made them all. Many of them multiple times. I've been cooking and collecting recipes since I was 10-years-old.
I keep a written calendar of our menus and usually have my menus outlined for about 2 months in advance. Most evenings for dinner we have a new untried main dish. One month out of the year, each evening meal is a review of TNT dishes.
"As a girl I had zero interest in the stove." - Julia Child
This is real inspiration. Look what Julia became!