I serve about 90% backhand on the backhand corner, 5% on the forehand corner, about 2.5% forehand on the backhand corner and the rest forehand on the forehand corner.
Depending on the opponents, serving at various corners sometimes give some surprising effective results, I found that serving heavy short back/side-spin from the forehand corner to the opponent's forehand small triangle (inside the table) is the most effective serve against right handed player (at my level, of course).
