Language barriers at work. Best Buy help?

Hello, I am a computer rep at Best and I often have to deal with hundreds of tourist that I can't communicate with. However, someway or another, I find a way to get around the problem and finish the job efficiently. HOWEVER... This upcoming Wednesday, Best Buy will be receiving usual amounts of tourist particularly Brazilians. Literally dozens of buses will line up and my concern is communication... What can I do to communicate with all these tourist without being overwhelmed by frustration... Now, I can speak Spanish well, but not 100% fluently, so that puts me slightly at ease since Spanish is similar to Portuguese. But I have received customers in the past that know nothing of English nor Spanish... How can I offer everything and close a sale without frustrating myself of the customer...? Are there any words that will help me and I can practice by Wednesday?