Following are some rule of thumb (ROT) passing guidelines. There certainly are situations where a ROT does not or should not apply. An ROT should be used as a foundation on which to evolve decision making in players and not to be used as unbreakable laws.
short-short-long--after two short passes a longer third pass should follow. The reason for this ROT is that after two passes of short distance (say less than 15 yards), the defense's shape should be adjusted and pressuring the ball. By playing a long pass, the ball is moved out of the pressure area and into (hopefully)a less defended area, forcing the defense to move and shift again.
pass to the feet of a receiving player that is stationary or moving to the ball - if the player has momentum going to the ball or is not moving, that player will have difficulty reacting a ball that is too wide.
pass into space if the receiving player is moving--a ball into space allows the receiving player to run on it. A pass to the feet of a moving player has very little chance of success as the pass is generally behind the player, negating all advantage of the movement. A ball into space allows the receiver to decide when, where and how to play it.
make the longest, safest pass possible--the longer the pass, the more defense will have to adjust.
look to make penetrating passes that have an excellent chance of success - penetration causes the defense to backup and allows the attack to go forward. Penetrate as often and as far forward as possible.
play passes at angles - vertical or horizontal passes change levels in only one dimension, either vertically or horizontally. An angled pass causes the defense to adjust both vertically and horizontally. Also, receiving players are often in better position to receive and handle an angled pass.
pass the ball backwards (drop or negative space pass) to relieve pressure - perhaps the quickest way to move a ball from one side of the field is to drop it back. One of the best ways to open up "windows" for long penetrating passes is to drop the ball back away from pressure. Players that receive a ball played back to them have better opportunities to play it forward
restrict square passes to near the touchline and in the attacking third - an intercepted square pass in the middle of the field is death to a defense as it is hard to recover.
never play the ball across one's goal - see square passing above
the closer a team gets to its attacking goal, the shorter the passing distance--especially in the area on top of the penalty area, the passes at times may be as close as two yards. In contrast, the passes in the back should be 15 yards or more in most cases.
commit defenders before passing - if a player has space in front, the player should carry the ball forward as quickly as possible. As the defense, closes down, the player can then decide if a pass is the best choice. Unless there is an immediate scoring opportunity with a pass, the player should not give up the ball unless the defense has to adjust to the dribbler.
pass to the receiver's foot away from pressure--when passing to a player's feet, choose the side away from the defender to allow the receiver to shield the defender and prevent an interception.
use the appropriate weight and pass type - most receiving players can't handle an instep drive from 10 yards away about knee high. All passes should be firm, but easily to manage. A pass that is difficult to control requires the receiver to take time to ensure it does not get away. Keep the passes rolling on the ground as much as possible.
pass behind defender when possible--when a pass is behind a defender, that defender is out of the picture for a brief period. Passes behind a defender often causes a defender to choose whether to watch the ball or to watch the defender's mark. Anytime defenders must make an on-the-spot decision is good for the attack.
play to teammate's preferred foot (when possible) - if all the above are addressed, then the passer may want to consider extending this courtesy to his teammate.