how to optimize candlestick charts from finance

I am learning how to make candlestick charts with my computers. There are a number of libraries doing this already, but I have worked from scratch. Here is my example.

There seem to be variants out there with two colors or with auxiliary lines.

_{(source: github.io)}

http://sathomas.me/jsdataviz/images/graphs/candle.png

I am worried about things like color and proportion. Does the thickness matter? How can I help the readability of my chart making it friendly to the eye and uncluttered?

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It doesn't help that I have used random test data. Here is a more typical example in Black and White.