quite often i prefer to coach up age II players rather than age I especially if they are already at a good level or purchased in the auctions. coaching up 5 levels of Age I is a lot and I usually only aim for doing this for 2 to 3 of my Age I players. 

Kevin wrote an article ages ago where I think  he worked out if you could get a win and draw every session you could coach up 3 age I to 15, 3 age II to 16 and 3 age III to 16  Maybe even ab age IV as well 

I don't know anyone outside of Ian and Alon who win with that regularity to be able to do that. Me, personally, I find that I often only have enough CP to do the following:

* Coach all Age I players to 15

* Coach my GK 3 times

* Coach 1 or 2 Age II players 2 or 3 times. 

I never have any CP to coach a non-GK Age III+ player.

I have very limited experience thus far, but I've found it extremely difficult to coach up a sufficient number of players, even with a couple of extra wins that I maybe should not have had. I'm sure I'll eventually find the secret to success.

Mike - for Cartlon, you're going to want to spend a couple seasons going strong on youth players. 

I agree with Rob. Fully coach up one or two Age I players if you can, but otherwise just make sure you're bringing through youth players.