[detaro]

Having a certain level of familiarity with it helps: functions and some level of syntax are easy to look up if you forgot them, but the "how it works" should be deep enough in your brain that it comes back once you look at code. The more languages you know, the easier it is to link knowledge to other examples and remember it better.

This is the one thing I find "cheat sheet" summaries of languages helpful for: really quickly refresh memory of syntax and/or common pitfalls. Along the same lines, quick access to documentation. Don't hesitate to write down your own if you trip over things repeatedly.

Have an execution environment ready since you can't as reliably reason about code. For many languages a REPL is a good start, a nice IDE with debugger helps too.