As a person who's been living in Prague for 2 years and visiting this beautiful city a lot before that as well I feel like I can already give you some tips that would help you when visiting... and what else could I start with than with food!
As a tourist I prefer to try local dishes but it can sometimes be a bit tricky because the restaurants in the centres of big cities are usually really expensive and it's actually not guaranteed that the food there is good. Of course you can look at TripAdvisor and see the reviews but I think that the very best option is to ask locals! They know where to go for good food that actually tastes the way it is supposed to and what's more, it usually happens to be less expensive!