Q: My strategy is just to write everything as if it's in the key of C.
A: that is sometimes called an 'open key' and it is mainly used when it's just so all over the place it's not worth putting a key signature. i used an open key for a video where i transcribed and harmonized spoken language, as music. no sense putting a key because it was all over the place. but most 'reasonable' music should have a key signature