Preparation

How to build a web app

http://lifehacker.com/5336113/how-to-build-a-web-application-from-scratch-with-no-experience
https://css-tricks.com/app-from-scratch-1-design/

Ideas
https://www.quora.com/What-are-some-cool-ideas-for-a-hackathon
http://www.stupidhackathon.com/
https://bigdatahackathon.wordpress.com/ideas-team-formation/
Example: http://devpost.com/software/gopackme

How to combine front-end, back-end (Team work)

Hackathon Preparation
https://www.quora.com/How-do-I-even-do-a-hackathon
https://www.quora.com/topic/Hackathons
https://www.quora.com/Is-Parse-a-good-option-to-setup-a-backend-at-a-Hackathon
http://angelhack.com/peppermint-5-steps-from-idea-to-hackathon-winning-app/