Trading overnight is often easier and more trend bound then during the regular sessions but it can be hit and miss too. There are nights when nothing happens!
To have a robust system, you should really backtest on a number of different timeframes: during periods of strong uptrends; strong downtrends; and periods of extended consolidation. This way you'll identify the strengths and more importantly the weaknesses of your system. You may even want to...
.... assuming you have good trading ideas, I'd say:
1. Trade management (when the trade goes in you favour).
2. Risk management (when the trade does not go the way you envisioned).
3. Discipline to follow your set-ups (i.e. don't chase, don't trade via emotions).
Learning to code would take too long. Looking to SharkIndicator's Bloodhound and Blackbird. You'll be able to build a semi to fully automated trading systems without knowing how to code. I think Sharkindicator's tools are only compatible with Ninjatrader though. Hope this helps.