Its not like SnGs are a completely different game from larger tournaments. And the early phase of any tournament is not completely different from a cash game either. So to do well in any kind of poker, you basically need to be all-around well founded in the game. Know your preflop ranges, know how to C-bet flop, know how to continue on turns, know how to defend your blinds. And so on and so forth. Maybe you dont really need to understand deep stacked poker in SnGs, since you rarely play with more than 75BB, but this is the only real difference.