Do you have any tips for overcoming the sort of (mostly unintentional) boys-club atmosphere that can (in my experience) hamper young women just starting out in political or journalistic careers?
Doing your job well is always great revenge. The axiom about working twice as hard for half the credit usually applies. Lots of studies and anecdotal evidence points to the fact that women tend to be less self-promotional and self-aggrandizing than men, and it works against them, so work on being your own cheerleader. And then don't take shit work or shit talk from people if the dudes around you would or do stand up to it themselves.
Other than those work-arounds, work for social justice and gender equality, because that's the only real way to "overcome" it in the end.