I cant speak very well to composition, it is something i am also working on after about 18 months of this production adventure. Which is why my thoughts should be taken with a grain of salt.
I dont want to contradict others with much more experience, knowledge and skill, but as an alternative to finding what will work best for you: I am not convinced that learning a specific instrument other than the ones you are using is entirely necessary. Picking up a guitar or piano and going through that learning curve might not help a whole lot with the modular. Learning music theory is a totally different mode of thinking than the creative making mode. It can be really difficult to apply new, shaky knowledge of theory to the inspired, intuitive, flow state that i seem to be the most productive in.
Not that theory is bad, as most people seem to agree that it has helped them and they were glad to learn it, but you might not need a whole lot to help impose a helpful framework. I took some piano lessons and really tried to learn scales. Improvising with a couple that i am comfortable using have really helped things to sound more coherent and premeditated rather than randomly hitting keys. (try Cminor or Bmajor, they sound interesting and fit the hand better than most)
Practicing scales and learning chords etc has been rewarding as a concrete formulaic way of improving my technical skills. It is a tangible way of seeing progress as you become familiar, faster and more confident. Practice can be a good way to feel productive, to be engaging musically even when you dont feel particularly inspired. In this way it can be a gateway as sitting down to practice can lead to unexpected and interesting tangents as you discover little things that sound neat together.
While learning some limited amount of theory and traditional instrument technique has helped, it hasnt been as helpful as exploring ideas on approach, or technical aspects of Ableton, or a particular synth. And more importantly as @letteronsounds put it
So you should definitely just keep making bleeps and bloops. But you should also record them, even if you don’t think it is very good. Eventually you will have an accumulation of little voyages that you can puzzle together and make into compositions.
I stumbled across a recent interview:
One thing that stood out was that they all agreed that thinking or overthinking is bad. Paraphrasing Abayomi ‘I need to play with things, really interact with the sound so im not thinking, im not necessarily trying to get a particular sound’.
I would emphasize what @bobbcorr said about play. Like a child who learns from playing, doing, experimenting, making movements and seeing what happens. I think its important to have fun, that you can take ‘play’ seriously and turn it into ‘work’ as you develop something and continue to practice. Its easier to trust your intuition and the accumulated musical knowledge you have built up by listening when approaching music with a playful, exploratory and inquisitive nature.
I like @healthylives approach of ‘creating a feeling or narrative arc’. Think of how you are moving things along, introducing change and evolving the song. Sometimes i think of a piece as visiting a foreign city and as i walk through i hear the blacksmith shop, then as i pass by this sound i encounter another. They sound different but still remain in the same city or place within the context of the song.
Another shout out to @Ethan_Hein, his writings and approach to music have been inspiring and educational. I’ve had particularly good results studying and reproducing his transcribed rhythm patterns.
Sorry if i was rambling on and not quite addressing your question regarding composition.
