Bought a Rem youth rifle in 308 for my son who wants to go hunting this fall. I am new to the 308 world but do load for 30-30 so I thought a 150gr cast or less at a slow pace would be a good way to break him in with out developing any bad habits. Any advice on powder types and loads would help.

This is an excellent approach! The first centerfire rifle my son tried was my 308 with cast bullet loads. I used AA#5 (7gr) with a 170gr cast bullet for approx. 1200fps. Other good powders to try would include Unique, SR4759, Red Dot, etc. The Lyman Cast Bullet Handbook is a good source for load data using light charges of pistol powders.

We did the same with a 12 year old, although we used Speer 110 gr jacketed bullets. Don't remember the 'charge off-hand (i'm at work, book's at home), but it was very manageable, and he killed a nine-point his first year. We used a Rem Youth Rifle also.

Try this:
http://www.hodgdon.com/data/youth/index.php