Necessity is always the mother of invention. As a young wife I didn't have a lot of money to spend on fancy filing systems. Thirty eight years later I'm still using the same filing system because it works.
Keeping up with all those receipts for purchases is quite easy. We all know how difficult it can be to find a receipt to return a purchase when there is no system in place.
On top of my fridge you'll find a beautiful wide blue and white bowl. It is decorative, but it also serves a function. It is the recepticle into which I place almost all of my receipts. As I unload my packages, into the bowl the receipt goes. Periodically I go through the bowl throwing out those receipts I'll no longer need.
The only receipts that do not go into that bowl are for clothing/shoes/personal accessories and appliances.
I keep an envelope (just a regular letter envelope) in my dresser in the bedroom into which I place all receipts for clothing/shoes/personal accessories. I also put any tags that might contain special cleaning instructions for clothing or bed linens in that envelope. When I buy a watch battery the receipt goes into that envelope. A battery should last a year, so when my battery quits, I can check and see how old it is.
Appliance receipts are stapled to the instruction booklet that comes with the appliance. These booklets are placed in a large envelope and kept in my jelly cupboard with my cookbooks. They are available for quick reference anytime I need instructions on how to use a feature, like the self-cleaning oven on my range.
Credit card receipts are kept in my billfold until the statement comes. Then they are stapled to the statement and filed in my shoebox filing "cabinet". Actually I use a decorative photo box now, but I began with a shoe box. Inside the box are several business size letter envelopes. You can purchase a whole box of these for a dollar if you don't already have them on hand. I have one for electric, water, credit cards, insurances, phone and internet statements. I note on the statement the date I paid the bill and file it in the appropriate envelope within the shoebox. I keep the shoebox on a shelf in my bedroom closet.
Medical insurance EOB's are kept in a large manilla envelope. On the front of the envelope you can jot down the doctor, date, and patient name as a means of keeping track, crossing off the entry when you receive the EOB. Then, when you receive the doctor's bill, staple the staement to the EOB and note the date you paid the bill on the statement. You can have one envelope for the year for the whole family, or one envelope for each family member if you have a lot of doctor visits to keep up with. If any family member has a hospital stay, you may want an envelop for all associated statements for that hospitalization only. On the front of the envelope you can notate any special difficulties or allergic reactions, medications used, etc. that might be of interest in the future. Memory does not always serve us as well as we'd like and these notes may be invaluable in the future.
I keep one medical envelope for the whole family for the calendar year and notate when we each had tests like colonoscopies, bone density scans, PSA tests, lipid profiles and Pap Smears, etc. Since some of these tests are not necessary annually, it can be difficult to remember when you last had them. I carry this information forward when I start a new medical envelope for a new year.
Irreplacable documents or difficult to replace documents should be stored in a safe deposit box, generally available at any bank, or at the very least in a home safe that is fire proof.
To keep things simple if you're just beginning to get organized start with the bowel or a basket or some decorative recepticle without a lid that can be easily accessed and put every receipt in there. As it fills and you do your periodic clean out, you can begin to group things together, placing them in envelopes and eventually into your shoebox or large manilla enevelpe as the case may be.
Reading this is more complicated than doing this. Just get started with the bowl/basket, etc. and you're on your way to organized efficiency.