Ask HN: Automate Stock Trading?

I'm building an automated stock trading system for my personal investments. The plan is for the trades to be based on data ingested through past stock performance, current trend, fundamental analysis, performance compared to similar stocks, and other data sources added incrementally.

There is a learning curve in which I'm developing the initial algorithms that will help gain an advantage over simplistic human investing with the computer providing a more deterministic risk-reward management system that it will apply. Once this has been achieved, the goal would be to increase the ROI and maximize the final take-home profit (minimize tax where possible to increase effective ROI). I'm validating algorithms with a back testing approach, currently obtaining data from Quandl.

I'm planning to host this on AWS and use a combination of Python and R. I haven't decided on the datastore yet, but I'm open to suggestions.

Does HN have any suggestions or any tips from someone who has attempted to do something like this in the past, if so, please also briefly describe your past experience and current position with the project?

Thanks!