SHARE THE TALKING
If you're traveling or running errands together, explicitly divide the tasks. If he's bargaining for a better price on the hotel room, she's in charge of booking the bus tickets to the next destination.

LEARN FROM OTHER BEGINNERS
Couples can reinforce each others mistakes with repetition. Speaking to native speakers is essential for language mastery. But speaking to classmates from around the world even if they hesitate and drawl in an awkward accent improves comprehension, too.

CORRECT EACH OTHER--GENTLY
Actual dialogue:
He: You said "muchos gracias" it's "muchas gracias."
She: I know it's "muchas gracias"; I'm not stupid!
He: I know you know it's "muchas gracias," but you said "muchos gracias." You often do.
She: "I do?"
He: "Yup."
She: "Okay. Fine. Thanks for telling me."
Result: Slight sulk, but correct grammar.

MATCH YOUR CLASS TO YOUR LEARNING STYLE
If you don't like to talk in groups, get a private tutor. But if you like to discuss and dispute, go with a group (not too big five is probably the sweet spot).

SHARE WHAT YOU LEARNED AT THE END OF THE DAY
Articulating what you've learned can help you really digest and remember your day's lessons. Plus, your partner learns more, too.