I'm planning to train a SF from next season on. I have a 19yo U21 prospect who I have to train two more seasons in outside skills, so my future SF will receive also that training. I'd rather have a bit higher player with good outside skills (OD and JR at least 6 and PA at least 4 - JS, DR and HA are not that important for now because I will do a lot of 1 on 1 training for SF/PF) and decent inside skills (RE and ID 7).
After two seasons when my U21 player reaches 22 years, I will start in inside skills. After four seasons of training (two seasons: outside skills, two seasons: inside skills) I hope I will get the SF to start in DII where I plan to be from next season.
I'd recommend to anyone who trains SF to start with OD first, so your trainee fouls out less. Plus OD is slow to train and it's best to start early.