Oh gosh, it's soooo hard. Babies are always hard to tell if they will go one way or another but if they start with good foundations, you pretty much know where to look for improvements or faults. You really have to know the parents and the siblings (if there are any) to the breedings to know early on unless you have years and years and years of training and looking at goats.
I know a baby goat I like when I see it but I can't always point to what it is that I like about it that I don't see in others. Sometimes I pick one others don't like as much and it later blossoms into something wonderful. Other times I pick ones that turn out to be duds (at least to others). Lucky me, I could live vicariously and not do the picking with my pocketbook!
With your own goats, you always hope to improve upon the parents. So in theory, if you do that, ever few years you'll be selling off some of your senior stock (unless you have oodles of space and dough to support them). It's hard though, so many people get attached to their goats, at all ages, especially if something traumatic or nearly traumatic happened along the line. Decisions with small breeders often come about as a necessity - not enough space to keep them all.
Remember too that every person has what they like and don't like in a goat. We think we have some basics on what makes a good goat, as far as conformation and udder structure, etc., but personality plays a lot into it for me and every judge in every show will be different. Sometimes the same judge will judge the same goats in the same weekend and place them differently from show to show too!
For national shows, are you thinking about ADGA, AGS, something else?
I like to keep most of my proven lines to freshen my own daughters, I want my bucks to have several daughters freshen here for the first time so I can evaluate udder, without blaming something in my mind about a purchasers management that could have effected her if she freshens at another persons place. 
