What should the basis of my bird's diet be?
    The basis of your bird's diet should be high quality parrot pellets.  Some popular brands include Kaytee Exact, Hagen's Tropican, Roudybush, Zupreem, Pretty Bird, Harrison's, and several more.  They vary somewhat but are usually quite similar.  It is generally agreed that the best is Harrion's, but they're also by far the most expensive.  The truth is that they all provide a good, quality base to the diet and are unlikely to cause problems so long as the diet is otherwise healthy and varied.
    Pellets are a dry food that does not spoil, and they should be left in your bird's dish at all times.

Why should I feed pellets instead of seed?
    Up until a decade or two ago, seed was the accepted parrot diet.  In many cases, that was all that was fed.  However, seed is not a nutritional diet, much less a complete diet.  It is high in fat and vitamin deficient.  For proof of this, I suggest comparing the photos in older bird books to the photos in the latest bird books - you can easily see the difference in feather quality and overall health.
    Many people still feed seed, mainly out of ignorance.  A few have their own excuses.  I have heard some say that they feed seed because the pellet manufacturers don't know enough to make a complete diet.  That is a statement I agree with wholeheartedly - nobody knows enough about the nutritional needs of birds to make a diet that is "perfect".  But the pellet manufacturers, the scientists and the veterinarians all know enough about it that they can manufacture a diet that is many times better and more nutritional than a seed diet.
   Also, don't jump to the conclusion that seed is cheaper.  Good-quality seed actually runs about the same per pound as does pellets.  Even lower-quality, cheaper seed isn't much cheaper than pellets at all when you consider the amount that is wasted.  Parrots have to hull seeds - that's a lot of waste right there.  Most parrots also don't like one or more types of seed in any given seed mix, and that's another large percentage of waste.  Up to 50% of the seed will end up on the cage floor.... and on your floor.  Pellets are also cleaner than seed - there's no little hulls that go flying everywhere!

What else should I feed my bird?
    Regardless of whether you feed pellets or seed, those should not be the only thing your bird eats!  Especially if your bird eats seed, an effort needs to be made to make his diet more well-rounded and healthier.  But even pelleted diets need to be supplemented with other healthy foods.
    Almost anything that is healthy for you, is healthy for your bird and should be fed.  Vegetables, fruits, grains, even meats can be fed.  Vegetables should form a good percentage of the diet.  Fresh veggies are best, frozen is good too.  Canned veggies can be okay so long as you avoid the types with extra salt or preservatives added.  Fruits should be regarded as a treat because they contain a lot of sugar.  Pasta, rice, bread, seeds and nuts are all good additions to the diet.  Yes, seed - it can be a good addition to the diet, it just isn't a good diet on it's own!  Seed is especially healthy if it's sprouted.  When it comes to meat, most birds prefer white meats and these are better for them (no, it's not cannibalistic!).  Some really like red meats, and these are okay on occasion.
   There has been a lot of argument over dairy foods.  The problem is that birds are, naturally, lactose-intolerant.  Most dairy foods are very high in lactose, and can cause diarrhea in birds.  But, some dairy foods such as cheese, yogurt, and skim milk are very low lactose and can be fed so long as you don't feed very high quantities at one time.  And of course, dairy foods are otherwise healthy and a good source of calcium.
   How to feed these other foods is up to you.  Pet stores sell mixes with dried veggies, pasta and grains which intended to be cooked and fed to birds.  Many bird owners cook especially for their birds, making bird muffins and similar things.  One of the simplest ways to give veggies or other foods everyday is to freeze it in daily portions and then mircowave them.  But, probably the easiest way to add some variety to your bird's diet is to give him a little of whatever you're eating, assuming it is healthy!
    How much of your bird's diet should consist of "other"?  Most agree that the diet should be about 50-80% pellets to provide a healthy and nutrional basis to the diet.  The rest should consist of just about anything else!
 

What shouldn't I feed my bird?
    First, there is the "do not feed" list: chocolate, avocado, coffee and alcohol.  Chocolate is poisonous to most non-human animals, and can build up in their system if it's fed consistently.  Avocado is poisonous to birds, especially the heart.  Caffeine is usually considered the bad ingredient in coffee, but in fact coffee contains the same thing that's in chocolate.  Caffeine isn't any good either and should be avoided on general principle.  And of course, alcohol is a well-known poison with well-known side effects.  Even a small amount can cause serious damage to a bird.
    Besides those foods, avoid junk foods - foods that are high in fat, salt, and preservatives.  When it comes to fat, we humans have become a touch sensitive to this subject and in fact a little fat won't hurt your bird unless he is already overweight.  So, the occasional bite of pizza is fine.  In fact, other junk foods won't hurt your bird anymore than they hurt you - but they should be fed on only the rarest occasions so they don't become a habit.