Find a preshot routine that you are comfortable with and make it yours; never, never hit a shot without going through the routine.
Here's one I use:
Grab the club in the left hand so the handle is under the little finger fat pad, let the club be loose and move up and down. Decide where you want to hit to--make it a small target versus the fairway or green as a whole.
Look for any hazards and tee the ball on the same side as the worst hazard.
Walk behind the ball and pick a blade of grass or something in front of the ball leading to where you want the ball to go or to the right for a draw etc.
Walk near to the ball and put your feet together, aim your clubface, place your right hand on the club and lock it with the left, spread your feet to line up with the clubface. Take a practice swing near the ball, shuffle up to your address position, waggle a few times, and swing.
All this takes less than 30 seconds.