I have no business giving anyone advice on dealing with clutter, but here goes. The planner is a good idea, but I don't use one myself. Here is what I do with various categories of paper.
Schoolwork - I have two preschoolers, so I don't deal with that yet. I save all the artwork that my kids do in large rectangular boxes in the basement. EVERYTHING. God only know what I will do with it later
Coupons - get yourself a coupon file that you can keep in your purse or bag with lots of slots for sorting, and create categories that work for you. I keep a compartment open in the front to move anything into that I plan to use at the store that day, if I've managed to be that organized by the time I get to the store.
Recipes - store your recipes in a three-ring binder that you can stash in one of your kitchen cabinets. Use pocket dividers for the different categories, and stash the recipes you want to try in there under the appropriate category. Persuse frequently for meal planning, and you will find it again. Adopting this recipe method has greatly improved my life in the kitchen.
Mail - throw most of your mail out immediately, including catalogues that you don't plan to buy from and will only create lust in your heart. I highly recommend paying bills online through your bank, two set times a month. I use the first and the fifteenth, give or take a day or two (make sure one of these days is right after your credit card bill usually arrives, or you could get spanked). Then you can throw away everything but the actual statement (return envelopes, etc.). I stash this on top of my computer monitor until bill time, and then file them after they've been paid.
Doctor notices and party invites - I paper clip these to a calendar I have hanging near my phone. Not a great solution, but it works for me. I always procrastinate making appointments for myself, whereas if I didn't I could just throw this stuff away immediately!
These are just things that work for me, most recently adopted as I hone my SAHM/haufrau skills. Best wishes in your quest for a more serene space, whichever solutions you find. . .