The hardest thing to do is to hit a perfectly straight ball
. This is why the professionals make the ball fade or draw at will. This is not as difficult as it seems. Understanding the fundamentals and techniques of "working the ball" will give you greater control of your shots.
To hit a draw your swing path needs to be straight to the golf ball or at an inside to outward direction. The club face should be closed to the path. So if you wanted to hit a perfectly straight shot the path would be straight and the club face would be square. Make sure the club is closed for a draw by turning your forearms as you hit through the ball. Make them touch each other after impact. It would be best to exaggerate this and if you start hooking you can then set your club less closed and your path less exaggerated on an in to out path.
Ingrain this until you can make the ball turn to the left every time. Look at your divots and make sure that are going straight or to the right so that you know that your path is correct.
The opposite holds true for a fade. The club face is open to the swing path which would be either straight or going to the left for a right handed golfer. Aim your club to the left of the target and have your club face pointing to the right or directly at the target. Swing out to the left and keep the face open. Do not turn the club over at impact. Do not pronate your forearms as you finish through the ball.
Practice these shots on the range until you can make them go to either the left or to the right every time. Exaggerate the path or the club face angle if you have to. You can always adjust by lessening the path or the club face angle if you start to hook or slice.