I'm having a flurry of article ideas come to me at the moment. I find that article ideas are a lot like buses; I don't see one for ages and then three arrive all at once - leaving me bewildered as to where the hell they came from and which one I should jump on to take me to my desired destination. I even bought a folder (buy one get one free!) from Staples on Friday to accommodate my research so I don't get the information for each article mixed up. It pays to be organised in this game.
I find sending out pitches for articles regularly has always worked for me. I'm also trying to widen my net and pitch to magazines I haven't considered before. Sometimes the pitches work and I can get cracking on writing the article, sometimes it's a no from the editor and sometimes, frustratingly, you hear nothing. But I soldier on! What I don't do now, something I did in the early years, is write the whole article before I've had the pitch accepted by an editor. I might gather some research but I don't waste my writing time writing the complete article until I know the editor is interested in it. There's a future 'Mistake Writer's Make for you Alex! Unless you've done that one before.
I suppose the theme of this post is don't waste your time writing articles you don't have an editor interested in. Put your efforts in writing well the ones you know you have a chance of getting published. By all means I would make enquiries with editors as to whether they want articles on whatever it is you want to write, but don't write them and then try and market them. Even with magazines that accept fully formed articles without the pitch, it's still worth testing the water by contacting the editor on the likelihood that they would be willing to read it.
Being a published writer is a business and you wouldn't find a plumber (also a business) fitting a new bathroom for someone without knowing if it's something the person would like and whether they were getting paid for it or not! Be kind to yourself and your writing.