Was talking to a coworker about eating out at asian restaurants, in particular, the ones in Chinatown. One thing I always do is pay only with cash. A lot of those restaurants don't accept anything but cash anyway, so it's just as well, but even if a place does accept credit cards or debit, I won't use it. With small businesses and restaurants, I find that I just don't really feel comfortable giving them my credit card - the restaurants, especially. This goes for most restaurants in general - unless it's one of those where they bring the wireless credit card machine right to your table. Anyway, my point is, cash only. It's easier and safer.
The other thing is that if you're eating at one of those cheap wonton noodle places, please, please, please don't ever tip more than 10%. It's not necessary and I guarantee that the only people who do that are non-asians. The 15-20% tipping rule doesn't apply! That's not to say that if you're eating at a top notch Chinese restaurant with great quality food and service that you shouldn't tip well. I'm just saying that at the regular, everyday, cheap places, it's not the norm. If your bill was $30, then a $3 tip is fine, no more than $4 if service and food were exceptional. Don't you dare tip $6, or I'm going to have to smack you upside the head!
One other thing... I find that if an asian restaurant gets a lot of good reviews in the newspaper or media, and has mostly white clientele, then it's probably not very good. Case in point - Wild Rice in Vancouver. I hear lots of white people rave over this place, but I really don't know what they're talking about. It's Chinese food that's not quite right, and they charge double what it would cost a few blocks down in Chinatown proper. Plus they serve cocktails and it's got a funky decor. It's basically a white-ified/sanitized version of a Chinese restaurant for people who find that a a real Chinese restaurant is too ethnic for them. Let's use this analogy: Pier 1 Imports is to antique flea market furniture as Wild Rice is to Chinese food. Yeah, quote me on that!
On the opposite end of the scale, just because a place is dirty, cramped, gives bad service, yet has good food and looks authentic, doesn't mean it's good. Case in point - Phnom Penh in Vancouver. From what my coworker tells me, it's a dump, service is bad, the food's not that great, and it's overpriced. Oh, and most of the patrons are white. Check, check, and check. Granted, you don't necessarily go to Chinatown for the greatest service or atmosphere, but you damn well should have good, cheap food, and most of the patrons should be asian. If not, then the place either isn't as good or authentic as you think it is, or else you're getting ripped off.
My personal favourites in Chinatown - Hon's for wonton noodle soup, chow mein, stir-fries, and everything in between; and Kam Gok Yuen for roasted/bbq meats on rice (it's busy, it's not the most comfortable place, but the food is damn good, cheap, and fast). Goldstone Bakery has a huge restaurant in the back with decent HK style lunch specials - less rushed than the other two restaurants. Not great, but good, and again, cheap.
Final tip - don't use the bathrooms in any of these restaurants in Chinatown. Just don't do it. If you can hold it, walk over to Tinseltown and use the bathrooms there. You can thank me later.