Whether you're an art director or a copywriter, knowing how to use Adobe's Creative Suite is going to take you far in this business.
Copywriters, it helps to know your way around the programs. Just in case your partner is busy or absent or nonexistent and you need to get shit done asap. Even just being able to put things together to make a PDF is going to help you.
But art directors and designers - if you don't know how to use these programs - how to make layer comps, how to organise your files properly and how to design the shit out of ads - then you need to get to work. Immediately.
It's your job to know the ins and outs of Photoshop and inDesign - and shoot if you can throw in some AfterEffects and/or 3D imaging you're golden.
When it comes to your portfolio - having the work in your book look polished, professional and print-ready - stuff you'd see in a magazine or online or wherever for real for real makes a big difference.
Check out these sites for Photoshop Tutorials
Lynda.com (not free)
And promise me you won't commit any of these Photoshop Fails
Like this one from Business Insider