Hello Tom, I keep all my electronic receipts in a folder on my computer and the hard copy ones in an envelope. I also use Excel to record all of my receipts and income. At the end of the year I use this information to complete my tax forms, along with the information sent by either my employer (T4) or in my case, being retired the government.

I'm not sure what other people are doing, but I track this just like any other business. Keep a list (and printed receipts if possible) of any expenses, including Premium membership, domains, hosting, etc. Same for income - with this it may best to set up book accounts for each affiliate company you are signed up with and track income that way. One of the benefits is that it may also qualify as a home business, so keep records on your utilities, homeowners insurance, etc as well, and anything you might buy in the way of office furniture, computers, and things like that. If you need more detail than that, I'll be happy to help. I'm not a tax pro by any means, but I took a few courses to help me do the books for other business I run.
Hope this helps!