Ed
I`m fairly new my self,but my advice would be first to look at this (infact book mark it)
http://www.glbwiki.com/index.php?title=Leveling Basically the idea behind slow build is an attribute costs 1 Skill Point to advance it by 1,till it gets to 48 then it cost 2 SP to advance it by 1.
At 60 it becomes 3, at 68 its 4 for 1.
Save your initial 15 Skill points and train,in the case of your HB,Speed and Agility.
when you have trained them up high enough so that the 15 SP you had plus the SP you earn each level up allow you to take one of them to 48. Usually start with the skill that will be very highest when the player matures.
For your HB speed would be the safe bet. (can exchange Str or any attribute)
Now each time you level up,using the numbers on that chart,you see that speed will get a free level up every couple levels.
Each of those level ups now saves you 2 SP instead of 1,if you stick training speed to 60,you get 3 for free each level.
Also if you stick to putting SP into Speed till 60 or better,all the time you spend training your next skill to get attention can be trained way up,so it`s closer to 48.
Rinse and repeat.
Altho the bonus per level up decreases as you get bigger,you can imagine,after getting speed to 68,that it will sneak up to 70 and beyond later in his career due to the auto level increases,saving you a ton of SP in his life span.
Period where you will be unbalanced,but that why its called slow,you are giving up some of the now, for a better later.