I look for the ones with the most vitamin and mineral content. I also give my birds things like cheese toast and plain pasta. Eggs are okay for birds as long as they are boiled for 20 minutes to kill any bacteria. Be sure to wash all the dishes that contain fresh food before giving your bird seed in that dish. Also wash the water dish every day.
Birds have a way of enriching their water by dropping food in it.
My pet grey, Idgie, loves to dunk her monkey biscuit and millet seed in her water before she eats it. Birds are like most kids. They will not make wise nutritional choices on their own and are usually afraid of trying new foods. Be patient when offering new food and be sure to keep offering it until the bird accepts it. Use fresh or frozen vegetables but stay away from canned because of the sodium content.