I have lots of paper for taxes, receipts, statements, bills, letters, brochures. currently they are just tucked into various folders ad-hoc and put into a cabinet in no particular order.
Any tips or experience on how to sort things and keep them organized?
What remains depends on your life situation I suspect, but for ideas, here is what I do:
Some papers are truly important. I like to put those in one of those expanding files with multiple slots and a carry handle. I have one for my personal papers (will, passport, birth certificates etc), one for taxes and one for the house documents. These should be stuff that if the house is on fire, you want to grab and take with you.
Having taken care of the stuff you don't need in physical form, and the really important stuff you must curate carefully, that leaves a bunch of other stuff. In my case that is mostly product manuals and warranties, and personal and travel memorabilia. While I am not a hardcore GTDer by any stretch, I do follow it for filing: get a filing cabinet, a good label maker, hanging folders and file folders, and file the hell out of everything. For example for product manuals, have a hanging folder for kitchen appliances, put each separate manual in a file folder, label the folder with your labelmaker, insert file folder into hanging folder.
General clutter guidelines apply, like handle everything once, think about whether you really need this ever again (this is where scanning really helps you, as you don't have to agonise too much about the decision), etc.