This could turn out to be a great thread, as there are a lot of different ideas on this subject.
Let me start off with how I clean mine and you all can correct me and add to.
First thing to do with a new gun, is THROW away the internal strainers that come with the gun, Give them to someone you dislike that uses a different brand of paint then SPI>
I am not a believer in tearing the gun down for cleaning, in my book, its just adding to the chance of things wearing out.
I add urethane reducer, shake and spray out.
then I add a few more ounces, maybe four and spray until gone and one of the most important things i think you can do is hold the trigger a few seconds longer spray just air after the reducer is gone, this keep stuff from running down and settling in the fluid tip or air cap.
When the gun does need tearing apart for a deep cleaning, I have a gallon of "Carb cleaner" Berrymans brand, do not buy the other brand as it does not work, think its stp brand, learned that lesson the hard way.
Cost is about $25 at advanced or pep boys and will last for 5-10 years.
I disassemble the fun put all the parts in basket and gun case in gallon, soak for 5 minutes and have left as long as a week and never any harm done, same with plastic cups and the lids, do it all the time.
In five minutes I take my brushes to the parts and slosh in a quart cup of reducer and they are ready to go. this is easy and painless way to clean a gun.