an easy way to find work to help with on github is to go to hackaday or some other such 'hackaton/diyer' community and follow the project links -- you can spend the entire evening fixing foot-guns and lazy/naive implementations of fairly well understood early CS concepts -- that's not to say that professionals don't make the same mistake, but amateurs who are just trying to get something to work rarely hit the codebase again after the thing does what they want.
