The Zapier newsletter I just got had a link to this article from last year: How to Find the RSS Feed URL for Almost Any Site. It's got some good tips for sussing out RSS feeds, but I have a couple more.
I ran across two sites recently that should've had RSS feeds, but apparently didn't, at least according to Inoreader, my feed reader of choice. Inoreader usually does a good job of automatically detecting an RSS feed if it exists, but it didn't find one for www.canadianenergycentre.ca*, which is a WordPress site. Turns out if you simply add /feed to the end of the URL you'll be good to go. That may be true for all WordPress sites - worth a try at least. Not sure why Inoreader didn't find that, and I'm still waiting to hear back from their tech support.
The other site that's crying for a feed is The Far Side! I emailed to ask for one but never heard back, so I built one of my own using Feed43. I'm not posting it here for fear of it being removed, but you can build one yourself, or hit me up privately for the URL :-)
Long Live RSS!
*This site doesn't get any Google juice from an actual link from me