I've had a couple of dozen tips published over the years- in most of the major WW magazines, including two in Fine Woodworking.
You can submit tips via email or snail mail. The addresses can be found in the magazine or on their website. Shopnotes and Woodsmith also have an online submission form on their webites. You can request that the tip be evaluated for publication by either or both of these sister publications. I find their online submission procedures awkward and limiting.
Some magazines still pay in cash (typically $100) if the tip is published, the trend however seems to be to "pay" in gift certificates- Lee Valley, Woodcraft, etc. Some magazines pay when the tip is selected, some don't pay until it is published which can be up to a year or more! Some magazines pay more if the tip includes drawings and/or photos and most reward the Top Tip of the issue with more money/bigger gift certificate, or a tool (of their selection). I ALWAYS submit photos and/or SketchUp drawings. Two of my tips were selected as a Top Tips- one earned me a $250 Lee Valley GC; the payment for the other was a Shop Fox bench-top hollow chisel mortiser.
I've probably had almost as many tips rejected as accepted. Since I usually "shot-gun" my submissions, I have also had few accepted by more than one magazine. You can never tell what the magazines are looking for. Sometimes I'll see tips that are good ideas and sometimes they border on being ridiculous or even unsafe. Some are obvious and have being used by woodworkers for years.
The two biggest names in the tip game are Serge Duclos, who by his own admission has had over one hundred (several hundred?) tips published, sometimes two in the same issue, and Bill Wells. A month doesn't go by where I don't see one or more tips by one of these guys in at least one WW magazine. Some tips seem to be recycled or written by others and published previously. Unfortunately, there is no such thing as a "tips clearing house."
Once a magazine pays for your tip, they own it and can put it in tip books, video collections, etc. without paying you any more. I saw one of my previously published tips on the Freud website- Freud must have purchased it from the magazine. I still got credit, but no money.
