First pick a winner for all of the games, even the final championship game. You won't know who will win the semifinal playoff games at the time that you make your first round of all picks. But pick the team that you think will be the final champion.
Then after the playoff games, again pick the winner of the final championship game. You WILL know who will be in the championship game at that time. You have the choice of the team you picked the first time around for the championship, or you may pick either playoff winner, regardless of the two teams you picked the first time around as the playoff winners. So you can get:
0, 2, or 4 points from the semifinal games
0, 2, or 4 points from the championship game
for a total of 0 to 8 possible points.