The secret is in correct brushing. Teeth should be brushed at least twice a day paying particular attention to the area around the braces but there are certain foods that stain the teeth more than others.
Curry will leave yellow stains. I know this because I notice that when I have eaten it the stains will last a lot longer than other foods regardless of how much I try to clean them off, Tea and coffee also cause staining of the teeth so it might be a good idea to limit these drinks. Other foods to avoid are mustard, tomatoes, coloured soda and and red wine as these all cause staining.
Apart from that you should be able to enjoy most other foods. You will probably learn through trial and error which foods cause staining and which don't and when they are removed you can be proud of your straight white teeth.