How do you distinguish between standard Thai and Northern accents?

I'm heading to Chiang Mai for a vacation and I've been exclusively studying standard Central Thai audio files. I'm terrified that when I try to order food or ask for directions, I won't understand the local response because of the regional variants. Do people in the North appreciate it if I try to use a few local words, or should I stick to standard Thai to avoid confusion? I'm worried about looking like a fool if I mix them up.