Agree on the RCM, was a great publication with a number of very knowledgeable builders. I still have a significant number of those from my father.
R/C Scale Modeler is a magazine in print in England that is also very good, although to get a subscription in the states is a bit prohibitive cost-wise.
The tips and pro-advice that I'm seeing in the magazines lately just frustrate me. It isn't that they are completely wrong, it is that they often are what I'd describe as "amateurish"... or "you can do it that way, but there are 10 other better/easier/more accurate/consistent ways that will make your life easier that would have been better to publish."
I remember ~2 years ago there was advice on hinge installation that wasn't bad but wasn't great either. It was the most basic of basic information and the method they recommended leaves many people frustrated from my experience. I tried contacting them and having a constructive discussion about doing a part 2 that had some better tips and tricks.... they weren't interested... in some ways I get it... to them I'm a nobody that is just criticizing their work. I tried pretty hard to be a positive/constructive criticism nobody that tried to make the magazine better though...