I'm laying out my first board in EAGLE and using an ATMega64A. I've prototyped it using an Arduino mega (and handful of other components) but am wondering what sorts of supporting components I need to think about when moving away from an Arduino platform and to my own custom board? I've jumped around in the data sheet and found some information about handling unused I/O pins, programming (for various methods), various special pins (RESET, etc.), and power limits but haven't found a suggested example wiring diagram with respect to supplying power or anything other signals like I've seen in some others. Coming from an Arduino I've never had to worry about most of this and just hoping to minimize mistakes that could land me with boards that don't work.