To be honest if you don't know about boost, then I'm guessing you aren't going for a special type of play. In which case you really should be fine with HP-J and Str-J. I'm pretty sure you can give Squall both of those before leaving Garden. Leave characters on low health and keep pressing circle to get limit breaks, it's cheap, but Renzokuken with any kind of strength should walk you through the first three discs (Maybe four I usually stick at the end of disc three).