I'd give the same advice to someone wanting to learn to write as I would to someone in a slump, as I become at times. A famous mathematician once said that writing a proof involves times of doing something completely unrelated; the same is true for artistic work (proofs are a kind of art, after all). Go about your day, maybe make notes about interesting things that happen if you wish, but don't sit down and exercise your writing muscles for a while. At some point, you'll catch something - an idea, a start, and that's when you strike, throwing all your power behind this concept, no matter how foolish it may seem at the moment. Take a step back - and maybe it's not good. Totally fine. The point being, it's a baseline, a start, and sometimes that's all you need.

The doing something totally different can be something related in a sense - reading and researching other people's stuff is a source of inspiration, after all. It's not the only one, though. Once you've got an idea, however small, in mind, give it a form, using whatever technique you're most comfortable with. Build on it, adjust things that don't look quite right, and slowly, it'll look more palatable.

An example - the other day, I was minding my business, going for a walk, when I rubbed my fingers together. Almost immediately, I saw this picture of a person doing that same motion, and fire forming in their hand. Thus, Friction Amplification was born, a superhero power and a baseline for a Mutants and Masterminds campaign world that will never see play anytime soon. It came out of literally nowhere, as these things often do, and it's turned into something. That's the bizarre nature of creativity - it works on its own time.

I wish you the best of luck, Grinner.