What's a small misake that you've made from not knowing better that's easy to miss?
For me, I recently had to revamp something because I was taught to use PlayerPrefs for saving all game data and had to move everything to a JSON in order to make cloud saves work or even just transfering save files to other devices.
not referencing textures, but initializing every time
I'm fairly certain if you use the asset manager, you get textures and other assets passed by reference by default. I think this kind of kicked by butt at first with particles, since I needed to thenso something with particle effect pools, instead of just loading them as a particle effect in the asset manager to begin with.
not working with an atlas for assets
While I understand what an atlas is, I'm not sure how large of an atlas I should use or try to get away with. At the moment I usually put every different 'object' as it's own sprite sheet.