Phil's pinball 101:
Do not put your weight on the machine, you need to stand in a position where you are balanced enough to move the machine if you need to. You can't do this sitting down!
Know your enemy! Especially on later games where knowing the rules can make a huge difference.
Avoid the sucker shots, tempting targets etc which are there to drain your ball. Jet bumpers on TZ, for example.
Watch others play first! Even if you know the machine, see how it's playing. Do all the shots go down the left drain? Does it tilt easy? Are the flippers powerful enough to make that crucial ramp?
Identify what path the ball is taking. You need to be able to decide what's going to happen before it gets to the slingshot area, you should be identifying and planning what needs to be done about 1/3 up the table! Ideally you don't let the ball go near the out/in lanes and move it way from SDTM which bringes us to....
NUDGING: You need to influence the ball, this can be done with the plunger (at start of ball), flippers or nudging. It is impossible to influence the ball as you can't touch it! You can, however move the table under the ball. Nudging left should send the ball right al vice versa for right. You can also move the table up! This increases the impact on rubbers, posts etc and can cause the ball to jump out of harms way. A huge nudge is often not needed, subtlety is your friend!
Slinghots are not your friend, try to keep off them or break the back/forth motion between them with an upward nudge.
Practice flipper skills especially dead catching and post transfers. Remember that a ball moving at speed on the flipper will need a different aim than one at rest. One person once told me that the difference between making and missing a shot with a ball at full speed is... 3 MILLISECONDS! Don't know about you, but my reactions are not THAT good! Trap the ball, stop it then shoot. This goes double on any classic game.
Controversial bit:
DURING MULTIBALL DO NOT CRADLE THE BALLS! Ok, this goes against everyone else but here's my thinking:
1) You are scoring points at 1/3 the rate you are by using all 3 balls
2) You handicap the flipper you are cradling on, watch Bowen play and see how many times balls are lost cause the flipper can't be properly used.
You should keep the balls out of the way by utilising ramps, saucers, jets, scoops/subways etc. Yes, your MB may be shorter but you should score more points and jackpots.
It's more fun and the way it's meant to play the game!