Something I've found helps me is also spending some creative energy on another non-brickfilming subject as so that I don't accidentally think of too many ideas with a good portion of my imagination focused elsewhere.
For me this is Riigo-Faloo, I just spend lots of time (sometimes even hours a day) thinking things out, and putting down certain key details like names and dates into text files.
Since I've started this habit, I feel as though I've come up with significantly fewer brickfilming ideas, however, that's not a bad thing, as sometimes a simple idea could take me an entire year or so to execute since I usually make such large films.
But even with that, I still have far too many ideas, and I'm far too slow.
I decided to work on Darkmoor a year ago, and even put my current project to a halt because I had a miserable flickering problem, and I thought that in something like Darkmoor, the flicker wouldn't feel as bad because it was a dark and spooky film, thus flickering might actually complement that film. Though I hadn't made a good release in a while so I made my short Leprechauns in France film, but right before I starting filming I fixed my flicker. I went ahead and stuck to making Darkmoor though because my mind was still set on it.
At the moment, I'm unsure of what to do next. I'm not sure yet if I want to continue my Batman film, as the footage I've shot is rather stale and flickery now, and I haven't shot anything for the film in over a year. Once I'm finally done with Darkmoor, this might even be two years. However, the first act of the film works as its own video, so I could still just release that as a quick cool short. The rest of the film wouldn't work as well with the continuity, and it is also ridiculously over complex. Plus I'm not as keen on making a Batman film as I was before.
And after that I also have several ideas, three of which are Faloovian shorts, one about a bumbling clown secret police captain, one about goblin monarchy, and another about vampires first coming to Riigo-Faloo in search of ways to slay each other.
I also have these two very important story ideas, one being Vampire Cinema, and the other being An Adventure in Bogeyland. I feel like either of these would be really fantastic and also significantly easier to produce than I Am The night.
On top of that I also just recently though up another idea but I'm afraid that if I write it I'll like it too much and put Darkmoor on hold for a year or something.
Usually though, I think one of the best things to do is ask several people which idea they'd like to see. I find that always helps me think up an idea. Even if most people want the idea you end up making, it helps you come to realize how important that idea is to you.