So, now I am sharing that advice with you... It's so easy even the most organizationally challenged can do this and it doesn't have to be fancy...just functional.
Here's what I used:
A three ring binder (I wouldn't use anything smaller than a 1.5" or you'll soon find yourself buying a bigger one, my biggest is 3"), legal pads, dividers w/pockets, business card sleeves, gussetted binder pocket (I found mine at Staples), a three hole punch, a stapler, pens (both regular and perm marker...I used a Sharpie), and finally (if you have one) a label maker. I'm sure there are other organizing items available, but these are what I found work for me.
If you have access to a large hole punch (we used a 40 page punch) then you can put holes into the legal pad and keep one in each binder. These come in handy when calling about a particular bill or test result and when you need to jot down notes/questions during or after an office visit. Rule of thumb, write down the name of anyone you speak with, the date & time you spoke to them, details of the conversation, and if possible get a reference number.
Having a convenient place to store all the business cards from doctor's offices, intervention programs, therapist, equipment, etc...is great! I always have access to their number. Just make sure if you change doctors or if someone leaves the practice then change out/remove their card.
I prefer the divider with pockets on the front and back. Since I don't carry my three hole punch to their offices with me (the binder, diaper bag, iPad, purse, and Rae are enough thank you), it makes a great place to slide papers in for safe storage until they can be filed later.
These gussetted binder pockets are great for those smaller items like CD's, pamphlets, a pen (I usually have four in my purse), or any other misc item that you need to store in your Big Book of Boo Boo's.
I didn't take a picture of the inside of my binder after I put all my paperwork in because...well...it's private information, but I separated the doctors by specialty and frequency of our visits. The larger orange binder is our main Big Book of Boo Boo's. The pink binder are doctors we've seen maybe once or twice. The purple binder is just for Genetics (since we go to two different offices I felt it best to keep their information together). The black and white binder is for all the bills...organized by who is billing us and I only keep the most recent statement (I also keep ALL receipts of any payments we've made...same for any co-pays, but those are kept with the specific doctor we paid).
Once your Big Book of Boo Boo's is put together it's pretty simple to add information as it comes and is a great way to keep all the doctors on the same page during a visit (especially if you see one doctor at one practice and another somewhere else...the information doesn't always get shared in a timely manner). I can't tell you how many times I have had to reference one of these books! They truly are a life saver and if anyone else has to take your little one to the doctor the book contains pretty much everything they need to know. After working on these this afternoon, I realized that I need at least one more for Early Steps (back to Staples I go...).