Look at the design of commercially available equipment - I'm not suggesting that you copy them but rather learn from them. Ask yourself 'why did they put this component in?' and so on. The other day I had reason to open up a commercial device (ADAM 4572) and I found they used a protection method that I had also used. I was quite chuffed as they had obviously came to the same conclusion I did. I have disassembled code from fuel injection computers to mobile phones and learned lot of interesting techniques. Don't try and re-invent the wheel, learn from others then add your own twist on it.