Alright Chilluns, I guess I'll jump on in here!
Fishsticks is right to a point. True mastery at something usually implies as close to perfection in context to what you are focused on. At that rate, it will take a life time or two to master the classic palm. Mastery means no mistakes, which as a result, means that you cannot fumble or drop a coin from palm... EVER! Roth, Stone, and the other greats still drop coins; thus, no one has yet to perfect their palm.
Penguincdude, in two years your palm may have reached an acceptably proficient level, but I will be willing to cut my right hand off if you are telling me it is mastered in this time. I will, however, eat my words and write an appology if you allow for sufficient evidence to prove me wrong. No disrespect there, but it is crucial to our art that we are rational with ourselves and our claims, allowing us to then figure ways to better our selves. I would invite you to post a videe/picture of your palm so that we may all learn together how to further improve what we believe to be already perfect (I use that term loosely).
Now to address Cory the OP. You have the right idea. Hold a coin in palm whenever possible. BUT, that is not all that you will need to do in order to achieve proficiency in palming. You must also, periodically, check on the classic palmed coin. Make sure it is the right place and constantly critique the hand position until it is correct (meaning as natural as possible). Once the coin is in the correct place, hold it there for extended periods of time to allow muscle memory time to develop. Ambidextrous ability in the palm is not only important, without proficiency in both hands, you have an inapplicable palm when it comes to actual routining. You must be able to palm proficiently in both hands before even thinking about moving onto more advanced sleights in our field. That is an important point that all seem to over look.
Next thing, the Muscle Pass was mentioned. It was also mentioned in such a way, that you should disregard the entire post. Pretend it was never even posted, as distractions such as attempting a muscle pass will in actuality, hinder your ability to palm. It will absolutely destroy it! True success and proficiency with the Muscle Pass requires not only a great understanding in the mechanics of a classic palm, but the ability to palm a coin with the strength and precision to be able to shoot it several inches upward in a non-spinning, flat manner to an awaiting palm above.
Hope this clears up any confusions among many of you, and offers some helpful tips and insight to allow you all to improve your coin magic from all angles.
Please, please do not hesitate to PM me or post any questions. I am more than happy to answer all that may arise.
All the best,
-Chase