Published book ideas come from two places:
1. You.
Not a surprise.
2. Your editor.
1. Always obey your editor.
2. Always obey your editor with a smile on your face.
But, what about MY ideas? Yes, of course. You can make suggestions or provide alternative rewrites, but only after you have obeyed your editor.
Showing them you’re right by disrespecting their directives may get you the book YOU want, but you certainly won’t be on the call list when they’re handing out ready-approved manuscript concepts. Which means, every book you write will fight an uphill battle to publication, just like the first one did.
To best prepare to be an oft-published author, prepare your attitude. Find a teacher, agent, friend and practice taking advice. Practice, practice, practice.
I just commented on your genre post, but now I see why you’re pushing to make the switch. ;p Again, best of luck!