Some Officers will want you off the bike, other will ask you to stay on, some will want you to remove your helmet, others not. I use a trick I heard about a while back. I usually remove my helmet, and as he's walking up to me (I make it a point to wait for this moment) I bend down and place the helmet on the ground near my back tire. Without being obvious, this places me in a subservient position. I don't know if the psychology works but I feel it does.
Universal rules: DO NOT ADMIT TO ANYTHING. If asked "How fast were you going?" I usually reply "that depends on where you clocked me" or something else similarly non-committal.
Attitude goes a long way. The comment about "doing better a few minutes ago" with a laugh is a good start. Remember, most of 'em are just doing their job.
Telling the officer where stuff is before reaching for it is good. After all, they're nervous too. Many officers have been hurt/killed during routine traffic stops.
And no, you cannot search my vehicle. Period. 4th amendment and all that. Get a warrant. I never carry anything I need to worry about, but that doesn't change the law.