Hmm things like that you usually learn best by practising and not from theory (at least in my Opinion) if you create the same Bug 2-3 times while Programming your mindset will change and you will always have it in your head before approaching to Code something.
And the thing with Tutorials is always dont take them step by step. Understand the reason why some things done in certain way (to avoid things I pointed out above)
And for Performance there is always a solid way to approach: Profile your Performance, Identify what is the Problem/Bottleneck, apply a apropriate fix. Repeat until you hit the Framerate you want.