Welcome to the hardest achievement of the entire game! This will take countless hours of practice and a little bit of luck...ok a lot of luck.
The best game mode to get this achievement is P1 vs P2, because you can basically set yourself up before you go for the 147.
Now, the way I got the achievement was starting with potting the free ball. The free ball becomes available when your opponent snookers you from every red on the table. You have to pot a colored ball(the free ball) in order to continue.
The best way to do this is to have P2 set up behind the brown ball and hit it slightly toward the blue ball. Then you are going to pot the brown ball with YOUR account in one of the far corner pockets down where the black ball is. Try to pot the black ball and position the cue ball to hit the reds after it strikes the black ball. This will give you a head start of 8 points and the best chance of getting the 147 achievement!
During my achievement winning run I had a break of 153. I potted 13 black balls and 2 pink balls. So it gives you a little wiggle room to pot other colored balls on the table when you can't pot the black.
Have fun with this one! I know I sure did...