Friend, Two most difficult problems of software engineering is Naming Variables and Invalidating Cache (when to do, when not to do etc).
Use camelCasing (no underscore please) and I am okay with bigger names because at least gives you idea in one go that what it does or is being used for. Try to use similar kinds of word through out the app like if you are using loginButton, follow same pattern rather then saying loginActionButton or something somewhere else.