I cannot imagine attending a hackathon without a branching strategy. It may be out of touch for some beginners but I highly recommend Nvie's GitFlow (https://github.com/nvie/gitflow).

My first hackathon was one of the best coding experience's I have had since jumping into the programming community but... man, it would've been so much better if my team didn't have an anxiety attack every time we merged code. It also saves you a ton of time which is crucial at a hack.