Artificial Intelligence is a rapidly growing field, and a cool one might I add
As for AI, Andre LaMothe''s Windows Game programming book is an excellent primer. However, there are few real books on the subject that go deeper than the philosphical view points.
The internet has dozens of good sites. But again where do you start? Try searching (my fav) Neural Networks, Fuzzy Logic, Machine Learning, or Expert Systems (sorta OT).
And, if you have the time, check this out. http://ai.iit.nrc.ca/subjects/ai_subjects.html
But generally,AI, is can be as complex as you want. I make a flow chart describing the logic the program takes based on several inputs. This will keep your errors down to a fairly low minimum. Just remember what the program is doing and keep to it. After all do you need to make HAL for a game of MahJongg?
A little warning on your quest for AI. The more advanced NeuralNets require a good knowledge of calculus/linear algebra which is covered in approx the first years at university. But such math-knowledge is only needed if you want to really understand what is going on in the neuralnets, and know what they can accomplish.
The best way to do it is just like what some people said, learning it from books, tutorials, and go to college is very usefull. I am a programmer and one of the best ways to learn is practice. Make your own ways to test it, and improve them till the ai is almost perfect! discribe every detail of the ai till the ai you made is almost like a real human brain! so build up a great ai by using randomized numbers, write all ai responses, and split your ai in a few directions. ( every section has to be described perfectly)
If you want a book on the philishopical side of AI "The Mind''s I" is a must read, its the best book on AI that I''ve read. Although it doesn''t go show you how to code AI it gives you some facisnating concepts about AI and the human mind, everyone intrested in AI should have it, anyone whose human should have it, after all you can''t model a brain without understanding it first.