A rough gauge would be 1/focal length for 'steady' shots. No, if you have unstable hand, you should use a tripod, not use modes to compensate for it. Give it a try, practice shooting and you can control all the settings one day.
thanks for the replies bros.... anyway im still under training for wedding shots tats y i cant use tripods, though is a gud suggestion but definately i cant carry the tripod while keep chasing for position to shoot the bride and groom right? i actually tried m mode but somtimes my pic turns blur coz of my unstable hands... and discover tat using shutter mode helps me alot