Design is definitely not my strong point either :) Google's design pages[1] have been a big help to me, they call out specific things to do and not to do with Material design. I think they put it together in a way that can help engineers out.
The app looks really useful and props on getting it out there. Another design related suggestion (especially for an app that features color so prominently) is to find a good color palette at a site like http://www.colourlovers.com/ and stick with that. No one should be picking their own colors in 2015 :)
[1] https://www.google.com/design/spec/style/typography.html#typ...