The following strategy note should be in the Othello rules.
GOOD SPACES:
A B C D E F G H
1 X . X . . X . X 1 2 . . . . . . . . 2 3 X . X . . X . X 3 4 . . . . . . . . 4 5 . . . . . . . . 5 6 X . X . . X . X 6 7 . . . . . . . . 7 8 X . X . . X . X 8
Until the end game, just look to those squares. If you have one, it is good. If you play next to one and let your opponent take it, that's bad.
Cheers, Mathijs.