1. If it comes with naan, eat it. that will usually buy you 5-10 minutes on the train ride home...
2. Ignore your doubts, if the kitchen sounds like world war 3, and the chef looks like a war refugee, that currys going to be epic.
3. pay attention to your doubts. if the bollywood music playing in the shop sounds clear, and theres less than an inch of dust on the sexually suggestive ethnic portraits, that curry is going to need a diaper with it.
4. pick routes with lots of pubs. sure, that curry shop might only be 3 blocks from your house, but stumbling dazed from toilet to toilet on the way home is common. The barman always knows dehli belly when he sees it.
5. If you've eaten kebab for lunch, and follow it up with curry for dinner, make sure your 4:00 tea includes a last will and testament.