Inhibit daydream mode and keep sessions limited to 30 minutes to an hour exercises maximum session playing  scales , plus music with breaks in between. This promotes a methodical and tactical approach rather than a dis-engaged marathon session i.e. inhibit the  temptation to practice  the habit of  playing in 'switched off' mode over and over, and over ,and over, and over , and over, and  then over again,  and then repeating, over and over and over....and over .......and over. Point made.

5 - 10 minutes Warm up exercises to get your fingers moving and to set some precision in your playing - Sevcik , arpeggios, scales G D A major 

Starting a new piece 
1. Look at the key signature and before playing the piece run through two alternative positional scales to figure out the positional options and predict where you are going to be likely to be playing the piece - yes it could be in half position as its in Bb but it could also be III1/2. 
2/. Avoid the Leap of Faith  - Look for the highest note - how will you get there without a sudden extreme positional change  - there is usually a way to break down positions to make the rise in manageable stages.
1. work out where unexpected   notes or rhythms are, high notes exist, write in the names of a high note F# etc  
Look for accidentals everything else should be in the key signature. 
2. Spot the obvious scale or arpeggio  in the piece  i.e. if the key is G major  look for the run of notes 
3.  Spot any repeated bars or sections
4.  Always practice under tempo with a metronome - you are practicing the flow . Inhibit the temptation to play fast - that bit is easy once you know what you are doing.  Think of the analogy of pulling a  rope through a pulley - it will always jam at a knot. The purpose of playing slowly is to flush out where the 'knotty problems exist' not generate mistakes and practice them over and over. If you play fast you will play from 'Knot'  to 'Knot' , you won't get the musical flow of the whole piece,