And formal charges . Curved arrows show movements of electrons , not atoms, not nothin' else. So, if you can draw the correct Lewis structure, get the formal charges right, understand electronegativity, relative acidity and basicity, thermodynamics, kinetics, and equilibria, then you can be assured that mechanisms will come easy. If you can't do these things, I can guarantee you'll be lost. Again, you cannot memorize mechanisms .
Every new problem is a different situation.
You have to understand mechanisms .