A pulled golf shot has a straight flight but it starts left of the intended target line and stays on that line, missing the target left. Pulled golf shots are caused by a club head moving too much on the inside of the target line after impact, rather than moving down the target line and the club face is pointing in the direction that the club head is moving. To correct pulled golf shots, you simply need to strike the ball and allow the club head to move more along the target line following the strike.
To encourage this movement in the club head, place a wood cover approximately 1 foot to the left of the ball and one to two inches on the inside (the side you stand on) of the target line. Make some swings and work on swinging the club head past the wood cover, on the far side of it, rather than pulling the club head in to the wood cover. As you do this, ensure that you keep the club face pointing towards your target. Now hit some balls with the wood cover in position and again work on swinging past the wood cover on the far side of it, with the club face pointing at the target.
If you find that you are hitting the wood cover a lot when trying this, then place a range basket to the right of the ball, about one inch and just on the outside (far side) of the target line. You should just be able to swing the club head away from the ball without catching the basket. Work on swinging the club back down to the ball without hitting the range basket. If your club head approaches the ball from inside the range basket, you will find that you swing through the ball and will now miss the head cover easily.
Work on this drill and once you are no longer catching either the range basket or the wood cover with the club head, you will be hitting much straighter and more accurate golf shots.