JMO - I believe that show attitude is born in them. You cannot create that attitude. That is one reason getting that "special" show dog is so hard to come by. For example I have several that love to be in the ring! They love to go in and show. The love to show the judge they have it all, that "terrier" attitude! And judges love it! You can have a gorgeous, very sound dog, but without that "it" attitude -it will most likely take longer to finish him/her.
Training - I start early (around 3 months) just getting them use to the lead on. Never make it work for them. Make it fun!! And you must practice a lot. Just getting the lead on them a few times or once a week on them before a show - isn't going to prepare them. You also must get them use to the sounds and sights of a show (there are so many people and so much going on). It is a lot for them to absorb all of a sudden. Great reason why to have puppy class.
Some breeders do keep their show dogs apart - the reason is to protect their show coat. I do allow mine to be together, since I prefer that. My coats could probably be longer on my dogs if I did not let them play together, longe on my sofa, and sleep with me. Oh, well!
Reason not to over spoil you show dog - you do not want them to hate being in the carrier during transportation to and from the show. This is for safety reason - using the carrier while in a car. I make mine feel special while we are going to a show. I give them lots of attention and treats. I play with them a lot and we have fun! Infact one of my girls - love to go off to shows since she knows she even will get a french fry or two.
I do not know it all and still constantly learning and trying new things. You have to try and see what works best for you and your dog.
T.