Since this is in the 'Songwriting' thread, I assume that you are talking about songwriting and not production.

In my opinion, songwriting takes both disciplined practice as well as playful wandering. The most important thing is having some means to track your writing; a place to jot down lyric ideas, to hum a melody, to take a note to 'copy the chord progression from song xyz'. This needs to be on you all the time.

The disciplined practice means often and regular. This often means not finishing something. Sometimes it means practicing a songwriting method. For example, have you ever tried writing a song with a refrain line? No? Go try that - now!

Have you ever tried using the minor 4th chord in a song? No? The Beatles did it often; go try that.

Have you gone the 'wrong' way around the circle of 5ths?

These are exercises not unlike practicing drum rudiments, or finger exercises on piano. Practice using them, and they will eventually make their way into your songwriting.

You don't just sit down and decide you will learn Für Elise on piano in a single, unbroken session - or never play anything else until you've learned it fully.

Why would you expect to do the same with songwriting?

Take advantage of every learning resource and resolve to attempt to put to use something that you've learned. Pat Pattison's songwriting course from Berklee is a great free resource primarily for lyric development.

I've been through it twice with an on-line cohort. I have forgotten most of what I learned, but I do remember two things that have made their way into nearly every song I've written since (35 songs since):

1. The Boxes (story development)
2. Bridges or pre-choruses with odd number of phrases are almost always more interesting than those with an even number of phrases.

He gives plenty of examples of these two ideas. I HAD to put them into practice for assignments for the classes. Now they almost come naturally.

I saved the videos from the classes. I should probably review them for new stuff to make 'normal' for me.

As for musical idea starters, I mine my friend Matt Blick's "Tickets To Write" website for little tidbits on common elements of Beatles songs. http://beatlessongwriting.blogspot.com/p/tickets-to-write.html

There's so many ideas to kick off music in that site.

Trying these different things in QUANTITY, will eventually lead to QUALITY now and then.